From: SeongJae Park <[email protected]>
Changes from Previous Version
=============================
- Drop loadable module support (Mike Rapoport)
- Select PAGE_EXTENSION if !64BIT for 'set_page_young()'
- Take care of the MMU notification subscribers (Shakeel Butt)
- Substitute 'struct damon_task' with 'struct damon_target' for better abstract
- Use 'struct pid' instead of 'pid_t' as the target (Shakeel Butt)
- Support pidfd from the debugfs interface (Shakeel Butt)
- Fix typos (Greg Thelen)
- Properly isolate DAMON from other pmd/pte Accessed bit users (Greg Thelen)
- Rebase on v5.8
Introduction
============
DAMON is a data access monitoring framework subsystem for the Linux kernel.
The core mechanisms of DAMON called 'region based sampling' and 'adaptive
regions adjustment' (refer to 'mechanisms.rst' in the 11th patch of this
patchset for the detail) make it
- accurate (The monitored information is useful for DRAM level memory
management. It might not appropriate for Cache-level accuracy, though.),
- light-weight (The monitoring overhead is low enough to be applied online
while making no impact on the performance of the target workloads.), and
- scalable (the upper-bound of the instrumentation overhead is controllable
regardless of the size of target workloads.).
Using this framework, therefore, the kernel's core memory management mechanisms
such as reclamation and THP can be optimized for better memory management. The
experimental memory management optimization works that incurring high
instrumentation overhead will be able to have another try. In user space,
meanwhile, users who have some special workloads will be able to write
personalized tools or applications for deeper understanding and specialized
optimizations of their systems.
Evaluations
===========
We evaluated DAMON's overhead, monitoring quality and usefulness using 25
realistic workloads on my QEMU/KVM based virtual machine running a kernel that
v16 DAMON patchset is applied.
DAMON is lightweight. It increases system memory usage by only -0.25% and
consumes less than 1% CPU time in most case. It slows target workloads down by
only 0.94%.
DAMON is accurate and useful for memory management optimizations. An
experimental DAMON-based operation scheme for THP, 'ethp', removes 31.29% of
THP memory overheads while preserving 60.64% of THP speedup. Another
experimental DAMON-based 'proactive reclamation' implementation, 'prcl',
reduces 87.95% of residential sets and 29.52% of system memory footprint while
incurring only 2.15% runtime overhead in the best case (parsec3/freqmine).
NOTE that the experimentail THP optimization and proactive reclamation are not
for production, just only for proof of concepts.
Please refer to the official document[1] or "Documentation/admin-guide/mm: Add
a document for DAMON" patch in this patchset for detailed evaluation setup and
results.
[1] https://damonitor.github.io/doc/html/latest-damon/admin-guide/mm/damon/eval.html
More Information
================
We prepared a showcase web site[1] that you can get more information. There
are
- the official documentations[2],
- the heatmap format dynamic access pattern of various realistic workloads for
heap area[3], mmap()-ed area[4], and stack[5] area,
- the dynamic working set size distribution[6] and chronological working set
size changes[7], and
- the latest performance test results[8].
[1] https://damonitor.github.io/_index
[2] https://damonitor.github.io/doc/html/latest-damon
[3] https://damonitor.github.io/test/result/visual/latest/rec.heatmap.0.png.html
[4] https://damonitor.github.io/test/result/visual/latest/rec.heatmap.1.png.html
[5] https://damonitor.github.io/test/result/visual/latest/rec.heatmap.2.png.html
[6] https://damonitor.github.io/test/result/visual/latest/rec.wss_sz.png.html
[7] https://damonitor.github.io/test/result/visual/latest/rec.wss_time.png.html
[8] https://damonitor.github.io/test/result/perf/latest/html/index.html
Baseline and Complete Git Trees
===============================
The patches are based on the v5.8. You can also clone the complete git
tree:
$ git clone git://github.com/sjp38/linux -b damon/patches/v19
The web is also available:
https://github.com/sjp38/linux/releases/tag/damon/patches/v19
There are a couple of trees for entire DAMON patchset series. It includes
future features. The first one[1] contains the changes for latest release,
while the other one[2] contains the changes for next release.
[1] https://github.com/sjp38/linux/tree/damon/master
[2] https://github.com/sjp38/linux/tree/damon/next
Sequence Of Patches
===================
First four patches implement the target address space independent core logics
of DAMON and it's programming interface. The 1st patch introduces DAMON
subsystem, it's data structures, and the data structure related basic
manipulation functions. Following three patches (2nd to 4th) implements the
core mechanisms of DAMON, namely regions based sampling (patch 2), adaptive
regions adjustment (patch 3), and dynamic memory mapping change adoption (patch
4).
Now the essential parts of DAMON is complete but require low level primitives
to be implemented and configured with DAMON to just work. The following two
patches makes it just work for virtual address spaces monitoring. The 5th
patch makes 'PG_idle' could be used by DAMON and the 6th patch implements the
virtual memory address space specific low primitives using page table Accessed
bits and the 'PG_idle' page flag.
Now DAMON just works for virtual address space monitoring via the kernel space
api. Following six patches adds interfaces for the users in the user space.
The 7th patch implements recording of access patterns in DAMON. Each of next
two patches (8th and 9th) respectively adds a tracepoint for other tracepoints
supporting tracers such as perf, and a debugfs interface for privileged people
and/or programs in user space. 10th patch makes the debugfs interface further
support pidfd. And, the 11th patch implements an user space tool to provide a
minimal reference to the debugfs interface and for high level use/tests of the
DAMON.
Three patches for maintainability follows. The 12th patch adds documentations
for both the user space and the kernel space. The 13th patch provides unit
tests (based on the kunit) while the 14th patch adds user space tests (based on
the kselftest).
Finally, the last patch (15th) updates the MAINTAINERS file.
Patch History
=============
Changes from v18
(https://lore.kernel.org/linux-mm/[email protected]/)
- Drop loadable module support (Mike Rapoport)
- Select PAGE_EXTENSION if !64BIT for 'set_page_young()'
- Take care of the MMU notification subscribers (Shakeel Butt)
- Substitute 'struct damon_task' with 'struct damon_target' for better abstract
- Use 'struct pid' instead of 'pid_t' as the target (Shakeel Butt)
- Support pidfd from the debugfs interface (Shakeel Butt)
- Fix typos (Greg Thelen)
- Properly isolate DAMON from other pmd/pte Accessed bit users (Greg Thelen)
- Rebase on v5.8
Changes from v17
(https://lore.kernel.org/linux-mm/[email protected]/)
- Reorganize the doc and remove png blobs (Mike Rapoport)
- Wordsmith mechnisms doc and commit messages
- tools/wss: Set default working set access frequency threshold
- Avoid race in damon deamon start
Changes from v16
(https://lore.kernel.org/linux-mm/[email protected]/)
- Wordsmith/cleanup the documentations and the code
- user space tool: Simplify the code and add wss option for reuse histogram
- recording: Check disablement condition properly
- recording: Force minimal recording buffer size (1KB)
Changes from v15
(https://lore.kernel.org/linux-mm/[email protected]/)
- Refine commit messages (David Hildenbrand)
- Optimizes three vma regions search (Varad Gautam)
- Support static granularity monitoring (Shakeel Butt)
- Cleanup code and re-organize the sequence of patches
Changes from v14
(https://lore.kernel.org/linux-mm/[email protected]/)
- Directly pass region and task to tracepoint (Steven Rostedt)
- Refine comments for better read
- Add more 'Reviewed-by's (Leonard Foerster, Brendan Higgins)
Changes from v13
(https://lore.kernel.org/linux-mm/[email protected]/)
- Fix a typo (Leonard Foerster)
- Fix wring condition of three sub ranges split (Leonard Foerster)
- Rebase on v5.7
Please refer to the v13 patchset to get older history.
SeongJae Park (15):
mm: Introduce Data Access MONitor (DAMON)
mm/damon: Implement region based sampling
mm/damon: Adaptively adjust regions
mm/damon: Track dynamic monitoring target regions update
mm/idle_page_tracking: Make PG_(idle|young) reusable
mm/damon: Implement callbacks for the virtual memory address spaces
mm/damon: Implement access pattern recording
mm/damon: Add a tracepoint
mm/damon: Implement a debugfs interface
damon/debugfs: Support pidfd target id
tools: Introduce a minimal user-space tool for DAMON
Documentation: Add documents for DAMON
mm/damon: Add kunit tests
mm/damon: Add user space selftests
MAINTAINERS: Update for DAMON
Documentation/admin-guide/mm/damon/guide.rst | 157 ++
Documentation/admin-guide/mm/damon/index.rst | 15 +
Documentation/admin-guide/mm/damon/plans.rst | 29 +
Documentation/admin-guide/mm/damon/start.rst | 96 +
Documentation/admin-guide/mm/damon/usage.rst | 302 +++
Documentation/admin-guide/mm/index.rst | 1 +
Documentation/vm/damon/api.rst | 20 +
Documentation/vm/damon/design.rst | 166 ++
Documentation/vm/damon/eval.rst | 222 +++
Documentation/vm/damon/faq.rst | 58 +
Documentation/vm/damon/index.rst | 31 +
Documentation/vm/index.rst | 1 +
MAINTAINERS | 13 +
include/linux/damon.h | 188 ++
include/linux/page-flags.h | 4 +-
include/linux/page_ext.h | 2 +-
include/linux/page_idle.h | 6 +-
include/trace/events/damon.h | 43 +
include/trace/events/mmflags.h | 2 +-
mm/Kconfig | 33 +
mm/Makefile | 1 +
mm/damon-test.h | 671 +++++++
mm/damon.c | 1732 +++++++++++++++++
mm/page_ext.c | 12 +-
mm/page_idle.c | 10 -
tools/damon/.gitignore | 1 +
tools/damon/_damon.py | 130 ++
tools/damon/_dist.py | 36 +
tools/damon/_recfile.py | 23 +
tools/damon/bin2txt.py | 67 +
tools/damon/damo | 37 +
tools/damon/heats.py | 362 ++++
tools/damon/nr_regions.py | 91 +
tools/damon/record.py | 135 ++
tools/damon/report.py | 45 +
tools/damon/wss.py | 100 +
tools/testing/selftests/damon/Makefile | 7 +
.../selftests/damon/_chk_dependency.sh | 28 +
tools/testing/selftests/damon/_chk_record.py | 109 ++
.../testing/selftests/damon/debugfs_attrs.sh | 161 ++
.../testing/selftests/damon/debugfs_record.sh | 50 +
41 files changed, 5179 insertions(+), 18 deletions(-)
create mode 100644 Documentation/admin-guide/mm/damon/guide.rst
create mode 100644 Documentation/admin-guide/mm/damon/index.rst
create mode 100644 Documentation/admin-guide/mm/damon/plans.rst
create mode 100644 Documentation/admin-guide/mm/damon/start.rst
create mode 100644 Documentation/admin-guide/mm/damon/usage.rst
create mode 100644 Documentation/vm/damon/api.rst
create mode 100644 Documentation/vm/damon/design.rst
create mode 100644 Documentation/vm/damon/eval.rst
create mode 100644 Documentation/vm/damon/faq.rst
create mode 100644 Documentation/vm/damon/index.rst
create mode 100644 include/linux/damon.h
create mode 100644 include/trace/events/damon.h
create mode 100644 mm/damon-test.h
create mode 100644 mm/damon.c
create mode 100644 tools/damon/.gitignore
create mode 100644 tools/damon/_damon.py
create mode 100644 tools/damon/_dist.py
create mode 100644 tools/damon/_recfile.py
create mode 100644 tools/damon/bin2txt.py
create mode 100755 tools/damon/damo
create mode 100644 tools/damon/heats.py
create mode 100644 tools/damon/nr_regions.py
create mode 100644 tools/damon/record.py
create mode 100644 tools/damon/report.py
create mode 100644 tools/damon/wss.py
create mode 100644 tools/testing/selftests/damon/Makefile
create mode 100644 tools/testing/selftests/damon/_chk_dependency.sh
create mode 100644 tools/testing/selftests/damon/_chk_record.py
create mode 100755 tools/testing/selftests/damon/debugfs_attrs.sh
create mode 100755 tools/testing/selftests/damon/debugfs_record.sh
--
2.17.1
From: SeongJae Park <[email protected]>
DAMON is a data access monitoring framework subsystem for the Linux
kernel. The core mechanisms of DAMON make it
- accurate (the monitoring output is useful enough for DRAM level
memory management; It might not appropriate for CPU Cache levels,
though),
- light-weight (the monitoring overhead is low enough to be applied
online), and
- scalable (the upper-bound of the overhead is in constant range
regardless of the size of target workloads).
Using this framework, therefore, the kernel's memory management
mechanisms can make advanced decisions. Experimental memory management
optimization works that incurring high data accesses monitoring overhead
could implemented again. In user space, meanwhile, users who have some
special workloads can write personalized applications for better
understanding and optimizations of their workloads and systems.
This commit is implementing only the stub for the initialization, basic
data structures, and simple manipulation functions of the structures.
The core mechanisms of DAMON will be implemented by following commits.
Signed-off-by: SeongJae Park <[email protected]>
Reviewed-by: Leonard Foerster <[email protected]>
Reviewed-by: Varad Gautam <[email protected]>
Signed-off-by: SeongJae Park <[email protected]>
---
include/linux/damon.h | 66 ++++++++++++++++
mm/Kconfig | 11 +++
mm/Makefile | 1 +
mm/damon.c | 176 ++++++++++++++++++++++++++++++++++++++++++
4 files changed, 254 insertions(+)
create mode 100644 include/linux/damon.h
create mode 100644 mm/damon.c
diff --git a/include/linux/damon.h b/include/linux/damon.h
new file mode 100644
index 000000000000..a6e839a236f4
--- /dev/null
+++ b/include/linux/damon.h
@@ -0,0 +1,66 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * DAMON api
+ *
+ * Copyright 2019-2020 Amazon.com, Inc. or its affiliates.
+ *
+ * Author: SeongJae Park <[email protected]>
+ */
+
+#ifndef _DAMON_H_
+#define _DAMON_H_
+
+#include <linux/random.h>
+#include <linux/types.h>
+
+/**
+ * struct damon_addr_range - Represents an address region of [@start, @end).
+ * @start: Start address of the region (inclusive).
+ * @end: End address of the region (exclusive).
+ */
+struct damon_addr_range {
+ unsigned long start;
+ unsigned long end;
+};
+
+/**
+ * struct damon_region - Represents a monitoring target region.
+ * @ar: The address range of the region.
+ * @sampling_addr: Address of the sample for the next access check.
+ * @nr_accesses: Access frequency of this region.
+ * @list: List head for siblings.
+ */
+struct damon_region {
+ struct damon_addr_range ar;
+ unsigned long sampling_addr;
+ unsigned int nr_accesses;
+ struct list_head list;
+};
+
+/**
+ * struct damon_target - Represents a monitoring target.
+ * @id: Unique identifier for this target.
+ * @regions_list: Head of the monitoring target regions of this target.
+ * @list: List head for siblings.
+ *
+ * Each monitoring context could have multiple targets. For example, a context
+ * for virtual memory address spaces could have multiple target processes. The
+ * @id of each target should be unique among the targets of the context. For
+ * example, in the virtual address monitoring context, it could be a pidfd or
+ * an address of an mm_struct.
+ */
+struct damon_target {
+ unsigned long id;
+ struct list_head regions_list;
+ struct list_head list;
+};
+
+/**
+ * struct damon_ctx - Represents a context for each monitoring.
+ * @targets_list: Head of monitoring targets (&damon_target) list.
+ */
+struct damon_ctx {
+ struct list_head targets_list; /* 'damon_target' objects */
+};
+
+#endif
diff --git a/mm/Kconfig b/mm/Kconfig
index f2104cc0d35c..a99d755d67d3 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -872,4 +872,15 @@ config ARCH_HAS_HUGEPD
config MAPPING_DIRTY_HELPERS
bool
+config DAMON
+ bool "Data Access Monitor"
+ help
+ This feature allows to monitor access frequency of each memory
+ region. The information can be useful for performance-centric DRAM
+ level memory management.
+
+ See https://damonitor.github.io/doc/html/latest-damon/index.html for
+ more information.
+ If unsure, say N.
+
endmenu
diff --git a/mm/Makefile b/mm/Makefile
index 6e9d46b2efc9..30c5dba52fb2 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -121,3 +121,4 @@ obj-$(CONFIG_MEMFD_CREATE) += memfd.o
obj-$(CONFIG_MAPPING_DIRTY_HELPERS) += mapping_dirty_helpers.o
obj-$(CONFIG_PTDUMP_CORE) += ptdump.o
obj-$(CONFIG_PAGE_REPORTING) += page_reporting.o
+obj-$(CONFIG_DAMON) += damon.o
diff --git a/mm/damon.c b/mm/damon.c
new file mode 100644
index 000000000000..d446ba4bfb0a
--- /dev/null
+++ b/mm/damon.c
@@ -0,0 +1,176 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Data Access Monitor
+ *
+ * Copyright 2019-2020 Amazon.com, Inc. or its affiliates.
+ *
+ * Author: SeongJae Park <[email protected]>
+ *
+ * This file is constructed in below parts.
+ *
+ * - Functions and macros for DAMON data structures
+ * - Functions for the initialization
+ *
+ * The core parts are not implemented yet.
+ */
+
+#define pr_fmt(fmt) "damon: " fmt
+
+#include <linux/damon.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+
+/*
+ * Functions and macros for DAMON data structures
+ */
+
+#define damon_next_region(r) \
+ (container_of(r->list.next, struct damon_region, list))
+
+#define damon_prev_region(r) \
+ (container_of(r->list.prev, struct damon_region, list))
+
+#define damon_for_each_region(r, t) \
+ list_for_each_entry(r, &t->regions_list, list)
+
+#define damon_for_each_region_safe(r, next, t) \
+ list_for_each_entry_safe(r, next, &t->regions_list, list)
+
+#define damon_for_each_target(t, ctx) \
+ list_for_each_entry(t, &(ctx)->targets_list, list)
+
+#define damon_for_each_target_safe(t, next, ctx) \
+ list_for_each_entry_safe(t, next, &(ctx)->targets_list, list)
+
+/* Get a random number in [l, r) */
+#define damon_rand(l, r) (l + prandom_u32() % (r - l))
+
+/*
+ * Construct a damon_region struct
+ *
+ * Returns the pointer to the new struct if success, or NULL otherwise
+ */
+static struct damon_region *damon_new_region(unsigned long start,
+ unsigned long end)
+{
+ struct damon_region *region;
+
+ region = kmalloc(sizeof(*region), GFP_KERNEL);
+ if (!region)
+ return NULL;
+
+ region->ar.start = start;
+ region->ar.end = end;
+ region->nr_accesses = 0;
+ INIT_LIST_HEAD(®ion->list);
+
+ return region;
+}
+
+/*
+ * Add a region between two other regions
+ */
+static inline void damon_insert_region(struct damon_region *r,
+ struct damon_region *prev, struct damon_region *next)
+{
+ __list_add(&r->list, &prev->list, &next->list);
+}
+
+static void damon_add_region(struct damon_region *r, struct damon_target *t)
+{
+ list_add_tail(&r->list, &t->regions_list);
+}
+
+static void damon_del_region(struct damon_region *r)
+{
+ list_del(&r->list);
+}
+
+static void damon_free_region(struct damon_region *r)
+{
+ kfree(r);
+}
+
+static void damon_destroy_region(struct damon_region *r)
+{
+ damon_del_region(r);
+ damon_free_region(r);
+}
+
+/*
+ * Construct a damon_target struct
+ *
+ * Returns the pointer to the new struct if success, or NULL otherwise
+ */
+static struct damon_target *damon_new_target(unsigned long id)
+{
+ struct damon_target *t;
+
+ t = kmalloc(sizeof(*t), GFP_KERNEL);
+ if (!t)
+ return NULL;
+
+ t->id = id;
+ INIT_LIST_HEAD(&t->regions_list);
+
+ return t;
+}
+
+static void damon_add_target(struct damon_ctx *ctx, struct damon_target *t)
+{
+ list_add_tail(&t->list, &ctx->targets_list);
+}
+
+static void damon_del_target(struct damon_target *t)
+{
+ list_del(&t->list);
+}
+
+static void damon_free_target(struct damon_target *t)
+{
+ struct damon_region *r, *next;
+
+ damon_for_each_region_safe(r, next, t)
+ damon_free_region(r);
+ kfree(t);
+}
+
+static void damon_destroy_target(struct damon_target *t)
+{
+ damon_del_target(t);
+ damon_free_target(t);
+}
+
+static unsigned int nr_damon_targets(struct damon_ctx *ctx)
+{
+ struct damon_target *t;
+ unsigned int nr_targets = 0;
+
+ damon_for_each_target(t, ctx)
+ nr_targets++;
+
+ return nr_targets;
+}
+
+static unsigned int nr_damon_regions(struct damon_target *t)
+{
+ struct damon_region *r;
+ unsigned int nr_regions = 0;
+
+ damon_for_each_region(r, t)
+ nr_regions++;
+
+ return nr_regions;
+}
+
+/*
+ * Functions for the initialization
+ */
+
+static int __init damon_init(void)
+{
+ return 0;
+}
+
+module_init(damon_init);
--
2.17.1
From: SeongJae Park <[email protected]>
DAMON separates its monitoring target address space independent high
level logics from the target space dependent low level primitives for
flexible support of various address spaces.
This commit implements DAMON's target address space independent high
level logics for basic access check and region based sampling. Hence,
without the target address space specific parts implementations, this
doesn't work alone. A reference implementation of those will be
provided by a later commit.
Basic Access Check
==================
The output of DAMON says what pages are how frequently accessed for a
given duration. The resolution of the access frequency is controlled by
setting ``sampling interval`` and ``aggregation interval``. In detail,
DAMON checks access to each page per ``sampling interval`` and
aggregates the results. In other words, counts the number of the
accesses to each page. After each ``aggregation interval`` passes,
DAMON calls callback functions that previously registered by users so
that users can read the aggregated results and then clears the results.
This can be described in below simple pseudo-code::
while monitoring_on:
for page in monitoring_target:
if accessed(page):
nr_accesses[page] += 1
if time() % aggregation_interval == 0:
for callback in user_registered_callbacks:
callback(monitoring_target, nr_accesses)
for page in monitoring_target:
nr_accesses[page] = 0
sleep(sampling interval)
The monitoring overhead of this mechanism will arbitrarily increase as
the size of the target workload grows.
Region Based Sampling
=====================
To avoid the unbounded increase of the overhead, DAMON groups adjacent
pages that assumed to have the same access frequencies into a region.
As long as the assumption (pages in a region have the same access
frequencies) is kept, only one page in the region is required to be
checked. Thus, for each ``sampling interval``, DAMON randomly picks one
page in each region, waits for one ``sampling interval``, checks whether
the page is accessed meanwhile, and increases the access frequency of
the region if so. Therefore, the monitoring overhead is controllable by
setting the number of regions. DAMON allows users to set the minimum
and the maximum number of regions for the trade-off.
This scheme, however, cannot preserve the quality of the output if the
assumption is not guaranteed. Next commit will address this problem.
Signed-off-by: SeongJae Park <[email protected]>
Reviewed-by: Leonard Foerster <[email protected]>
---
include/linux/damon.h | 89 ++++++++++++++-
mm/damon.c | 256 +++++++++++++++++++++++++++++++++++++++++-
2 files changed, 342 insertions(+), 3 deletions(-)
diff --git a/include/linux/damon.h b/include/linux/damon.h
index a6e839a236f4..0b1153971e6d 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -11,6 +11,8 @@
#define _DAMON_H_
#include <linux/random.h>
+#include <linux/mutex.h>
+#include <linux/time64.h>
#include <linux/types.h>
/**
@@ -56,11 +58,96 @@ struct damon_target {
};
/**
- * struct damon_ctx - Represents a context for each monitoring.
+ * struct damon_ctx - Represents a context for each monitoring. This is the
+ * main interface that allows users to set the attributes and get the results
+ * of the monitoring.
+ *
+ * @sample_interval: The time between access samplings.
+ * @aggr_interval: The time between monitor results aggregations.
+ * @nr_regions: The number of monitoring regions.
+ *
+ * For each @sample_interval, DAMON checks whether each region is accessed or
+ * not. It aggregates and keeps the access information (number of accesses to
+ * each region) for @aggr_interval time. All time intervals are in
+ * micro-seconds.
+ *
+ * @kdamond: Kernel thread who does the monitoring.
+ * @kdamond_stop: Notifies whether kdamond should stop.
+ * @kdamond_lock: Mutex for the synchronizations with @kdamond.
+ *
+ * For each monitoring request (damon_start()), a kernel thread for the
+ * monitoring is created. The pointer to the thread is stored in @kdamond.
+ *
+ * Once started, the monitoring thread runs until explicitly required to be
+ * terminated or every monitoring target is invalid. The validity of the
+ * targets is checked via the @target_valid callback. The termination can also
+ * be explicitly requested by writing non-zero to @kdamond_stop. The thread
+ * sets @kdamond to NULL when it terminates. Therefore, users can know whether
+ * the monitoring is ongoing or terminated by reading @kdamond. Reads and
+ * writes to @kdamond and @kdamond_stop from outside of the monitoring thread
+ * must be protected by @kdamond_lock.
+ *
+ * Note that the monitoring thread protects only @kdamond and @kdamond_stop via
+ * @kdamond_lock. Accesses to other fields must be protected by themselves.
+ *
* @targets_list: Head of monitoring targets (&damon_target) list.
+ *
+ * @init_target_regions: Constructs initial monitoring target regions.
+ * @prepare_access_checks: Prepares next access check of target regions.
+ * @check_accesses: Checks the access of target regions.
+ * @target_valid: Determine if the target is valid.
+ * @sample_cb: Called for each sampling interval.
+ * @aggregate_cb: Called for each aggregation interval.
+ *
+ * DAMON can be extended for various address spaces by users. For this, users
+ * can register the target address space dependent low level functions for
+ * their usecases via the callback pointers of the context. The monitoring
+ * thread calls @init_target_regions before starting the monitoring, and
+ * @prepare_access_checks, @check_accesses, and @target_valid for each
+ * @sample_interval.
+ *
+ * @init_target_regions should construct proper monitoring target regions and
+ * link those to the DAMON context struct.
+ * @prepare_access_checks should manipulate the monitoring regions to be
+ * prepare for the next access check.
+ * @check_accesses should check the accesses to each region that made after the
+ * last preparation and update the `->nr_accesses` of each region.
+ * @target_valid should check whether the target is still valid for the
+ * monitoring.
+ *
+ * @sample_cb and @aggregate_cb are called from @kdamond for each of the
+ * sampling intervals and aggregation intervals, respectively. Therefore,
+ * users can safely access to the monitoring results via @targets_list without
+ * additional protection of @kdamond_lock. For the reason, users are
+ * recommended to use these callback for the accesses to the results.
*/
struct damon_ctx {
+ unsigned long sample_interval;
+ unsigned long aggr_interval;
+ unsigned long nr_regions;
+
+ struct timespec64 last_aggregation;
+
+ struct task_struct *kdamond;
+ bool kdamond_stop;
+ struct mutex kdamond_lock;
+
struct list_head targets_list; /* 'damon_target' objects */
+
+ /* callbacks */
+ void (*init_target_regions)(struct damon_ctx *context);
+ void (*prepare_access_checks)(struct damon_ctx *context);
+ unsigned int (*check_accesses)(struct damon_ctx *context);
+ bool (*target_valid)(struct damon_target *target);
+ void (*sample_cb)(struct damon_ctx *context);
+ void (*aggregate_cb)(struct damon_ctx *context);
};
+int damon_set_targets(struct damon_ctx *ctx,
+ unsigned long *ids, ssize_t nr_ids);
+int damon_set_attrs(struct damon_ctx *ctx, unsigned long sample_int,
+ unsigned long aggr_int, unsigned long min_nr_reg);
+int damon_start(struct damon_ctx *ctx);
+int damon_stop(struct damon_ctx *ctx);
+
#endif
diff --git a/mm/damon.c b/mm/damon.c
index d446ba4bfb0a..63e434ab483f 100644
--- a/mm/damon.c
+++ b/mm/damon.c
@@ -9,18 +9,27 @@
* This file is constructed in below parts.
*
* - Functions and macros for DAMON data structures
+ * - Functions for DAMON core logics and features
+ * - Functions for the DAMON programming interface
* - Functions for the initialization
- *
- * The core parts are not implemented yet.
*/
#define pr_fmt(fmt) "damon: " fmt
#include <linux/damon.h>
+#include <linux/delay.h>
+#include <linux/kthread.h>
#include <linux/mm.h>
#include <linux/module.h>
+#include <linux/page_idle.h>
+#include <linux/random.h>
+#include <linux/sched/mm.h>
+#include <linux/sched/task.h>
#include <linux/slab.h>
+/* Minimal region size. Every damon_region is aligned by this. */
+#define MIN_REGION PAGE_SIZE
+
/*
* Functions and macros for DAMON data structures
*/
@@ -164,6 +173,249 @@ static unsigned int nr_damon_regions(struct damon_target *t)
return nr_regions;
}
+/*
+ * Functions for DAMON core logics and features
+ */
+
+/*
+ * damon_check_reset_time_interval() - Check if a time interval is elapsed.
+ * @baseline: the time to check whether the interval has elapsed since
+ * @interval: the time interval (microseconds)
+ *
+ * See whether the given time interval has passed since the given baseline
+ * time. If so, it also updates the baseline to current time for next check.
+ *
+ * Return: true if the time interval has passed, or false otherwise.
+ */
+static bool damon_check_reset_time_interval(struct timespec64 *baseline,
+ unsigned long interval)
+{
+ struct timespec64 now;
+
+ ktime_get_coarse_ts64(&now);
+ if ((timespec64_to_ns(&now) - timespec64_to_ns(baseline)) <
+ interval * 1000)
+ return false;
+ *baseline = now;
+ return true;
+}
+
+/*
+ * Check whether it is time to flush the aggregated information
+ */
+static bool kdamond_aggregate_interval_passed(struct damon_ctx *ctx)
+{
+ return damon_check_reset_time_interval(&ctx->last_aggregation,
+ ctx->aggr_interval);
+}
+
+/*
+ * Reset the aggregated monitoring results
+ */
+static void kdamond_reset_aggregated(struct damon_ctx *c)
+{
+ struct damon_target *t;
+ struct damon_region *r;
+
+ damon_for_each_target(t, c) {
+ damon_for_each_region(r, t)
+ r->nr_accesses = 0;
+ }
+}
+
+/*
+ * Check whether current monitoring should be stopped
+ *
+ * The monitoring is stopped when either the user requested to stop, or all
+ * monitoring targets are invalid.
+ *
+ * Returns true if need to stop current monitoring.
+ */
+static bool kdamond_need_stop(struct damon_ctx *ctx)
+{
+ struct damon_target *t;
+ bool stop;
+
+ mutex_lock(&ctx->kdamond_lock);
+ stop = ctx->kdamond_stop;
+ mutex_unlock(&ctx->kdamond_lock);
+ if (stop)
+ return true;
+
+ if (!ctx->target_valid)
+ return false;
+
+ damon_for_each_target(t, ctx) {
+ if (ctx->target_valid(t))
+ return false;
+ }
+
+ return true;
+}
+
+/*
+ * The monitoring daemon that runs as a kernel thread
+ */
+static int kdamond_fn(void *data)
+{
+ struct damon_ctx *ctx = (struct damon_ctx *)data;
+ struct damon_target *t;
+ struct damon_region *r, *next;
+
+ pr_info("kdamond (%d) starts\n", ctx->kdamond->pid);
+ if (ctx->init_target_regions)
+ ctx->init_target_regions(ctx);
+ while (!kdamond_need_stop(ctx)) {
+ if (ctx->prepare_access_checks)
+ ctx->prepare_access_checks(ctx);
+ if (ctx->sample_cb)
+ ctx->sample_cb(ctx);
+
+ usleep_range(ctx->sample_interval, ctx->sample_interval + 1);
+
+ if (ctx->check_accesses)
+ ctx->check_accesses(ctx);
+
+ if (kdamond_aggregate_interval_passed(ctx)) {
+ if (ctx->aggregate_cb)
+ ctx->aggregate_cb(ctx);
+ kdamond_reset_aggregated(ctx);
+ }
+
+ }
+ damon_for_each_target(t, ctx) {
+ damon_for_each_region_safe(r, next, t)
+ damon_destroy_region(r);
+ }
+ pr_debug("kdamond (%d) finishes\n", ctx->kdamond->pid);
+ mutex_lock(&ctx->kdamond_lock);
+ ctx->kdamond = NULL;
+ mutex_unlock(&ctx->kdamond_lock);
+
+ do_exit(0);
+}
+
+/*
+ * Functions for the DAMON programming interface
+ */
+
+static bool damon_kdamond_running(struct damon_ctx *ctx)
+{
+ bool running;
+
+ mutex_lock(&ctx->kdamond_lock);
+ running = ctx->kdamond != NULL;
+ mutex_unlock(&ctx->kdamond_lock);
+
+ return running;
+}
+
+/**
+ * damon_start() - Starts monitoring with given context.
+ * @ctx: monitoring context
+ *
+ * Return: 0 on success, negative error code otherwise.
+ */
+int damon_start(struct damon_ctx *ctx)
+{
+ int err = -EBUSY;
+
+ mutex_lock(&ctx->kdamond_lock);
+ if (!ctx->kdamond) {
+ err = 0;
+ ctx->kdamond_stop = false;
+ ctx->kdamond = kthread_create(kdamond_fn, ctx, "kdamond");
+ if (IS_ERR(ctx->kdamond))
+ err = PTR_ERR(ctx->kdamond);
+ else
+ wake_up_process(ctx->kdamond);
+ }
+ mutex_unlock(&ctx->kdamond_lock);
+
+ return err;
+}
+
+/**
+ * damon_stop() - Stops monitoring of given context.
+ * @ctx: monitoring context
+ *
+ * Return: 0 on success, negative error code otherwise.
+ */
+int damon_stop(struct damon_ctx *ctx)
+{
+ mutex_lock(&ctx->kdamond_lock);
+ if (ctx->kdamond) {
+ ctx->kdamond_stop = true;
+ mutex_unlock(&ctx->kdamond_lock);
+ while (damon_kdamond_running(ctx))
+ usleep_range(ctx->sample_interval,
+ ctx->sample_interval * 2);
+ return 0;
+ }
+ mutex_unlock(&ctx->kdamond_lock);
+
+ return -EPERM;
+}
+
+/**
+ * damon_set_targets() - Set monitoring targets.
+ * @ctx: monitoring context
+ * @ids: array of target ids
+ * @nr_ids: number of entries in @ids
+ *
+ * This function should not be called while the kdamond is running.
+ *
+ * Return: 0 on success, negative error code otherwise.
+ */
+int damon_set_targets(struct damon_ctx *ctx,
+ unsigned long *ids, ssize_t nr_ids)
+{
+ ssize_t i;
+ struct damon_target *t, *next;
+
+ damon_for_each_target_safe(t, next, ctx)
+ damon_destroy_target(t);
+
+ for (i = 0; i < nr_ids; i++) {
+ t = damon_new_target(ids[i]);
+ if (!t) {
+ pr_err("Failed to alloc damon_target\n");
+ return -ENOMEM;
+ }
+ damon_add_target(ctx, t);
+ }
+
+ return 0;
+}
+
+/**
+ * damon_set_attrs() - Set attributes for the monitoring.
+ * @ctx: monitoring context
+ * @sample_int: time interval between samplings
+ * @aggr_int: time interval between aggregations
+ * @nr_reg: number of regions
+ *
+ * This function should not be called while the kdamond is running.
+ * Every time interval is in micro-seconds.
+ *
+ * Return: 0 on success, negative error code otherwise.
+ */
+int damon_set_attrs(struct damon_ctx *ctx, unsigned long sample_int,
+ unsigned long aggr_int, unsigned long nr_reg)
+{
+ if (nr_reg < 3) {
+ pr_err("nr_regions (%lu) must be at least 3\n",
+ nr_reg);
+ return -EINVAL;
+ }
+
+ ctx->sample_interval = sample_int;
+ ctx->aggr_interval = aggr_int;
+ ctx->nr_regions = nr_reg;
+
+ return 0;
+}
+
/*
* Functions for the initialization
*/
--
2.17.1
From: SeongJae Park <[email protected]>
PG_idle and PG_young allows the two PTE Accessed bit users,
IDLE_PAGE_TRACKING and the reclaim logic concurrently work while don't
interfere each other. That is, when they need to clear the Accessed
bit, they set PG_young and PG_idle to represent the previous state of
the bit, respectively. And when they need to read the bit, if the bit
is cleared, they further read the PG_young and PG_idle, respectively, to
know whether the other has cleared the bit meanwhile or not.
We could add another page flag and extend the mechanism to use the flag
if we need to add another concurrent PTE Accessed bit user subsystem.
However, it would be only waste the space. Instead, if the new
subsystem is mutually exclusive with IDLE_PAGE_TRACKING, it could simply
reuse the PG_idle flag. However, it's impossible because the flags are
dependent on IDLE_PAGE_TRACKING.
To allow such reuse of the flags, this commit separates the PG_young and
PG_idle flag logic from IDLE_PAGE_TRACKING and introduces new kernel
config, 'PAGE_IDLE_FLAG'. Hence, if !IDLE_PAGE_TRACKING and
IDLE_PAGE_FLAG, a new subsystem would be able to reuse PG_idle.
In the next commit, DAMON's reference implementation of the virtual
memory address space monitoring primitives will use it.
Signed-off-by: SeongJae Park <[email protected]>
---
include/linux/page-flags.h | 4 ++--
include/linux/page_ext.h | 2 +-
include/linux/page_idle.h | 6 +++---
include/trace/events/mmflags.h | 2 +-
mm/Kconfig | 8 ++++++++
mm/page_ext.c | 12 +++++++++++-
mm/page_idle.c | 10 ----------
7 files changed, 26 insertions(+), 18 deletions(-)
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 6be1aa559b1e..7736d290bb61 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -132,7 +132,7 @@ enum pageflags {
#ifdef CONFIG_MEMORY_FAILURE
PG_hwpoison, /* hardware poisoned page. Don't touch */
#endif
-#if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
+#if defined(CONFIG_PAGE_IDLE_FLAG) && defined(CONFIG_64BIT)
PG_young,
PG_idle,
#endif
@@ -432,7 +432,7 @@ static inline bool set_hwpoison_free_buddy_page(struct page *page)
#define __PG_HWPOISON 0
#endif
-#if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
+#if defined(CONFIG_PAGE_IDLE_FLAG) && defined(CONFIG_64BIT)
TESTPAGEFLAG(Young, young, PF_ANY)
SETPAGEFLAG(Young, young, PF_ANY)
TESTCLEARFLAG(Young, young, PF_ANY)
diff --git a/include/linux/page_ext.h b/include/linux/page_ext.h
index cfce186f0c4e..c9cbc9756011 100644
--- a/include/linux/page_ext.h
+++ b/include/linux/page_ext.h
@@ -19,7 +19,7 @@ struct page_ext_operations {
enum page_ext_flags {
PAGE_EXT_OWNER,
PAGE_EXT_OWNER_ALLOCATED,
-#if defined(CONFIG_IDLE_PAGE_TRACKING) && !defined(CONFIG_64BIT)
+#if defined(CONFIG_PAGE_IDLE_FLAG) && !defined(CONFIG_64BIT)
PAGE_EXT_YOUNG,
PAGE_EXT_IDLE,
#endif
diff --git a/include/linux/page_idle.h b/include/linux/page_idle.h
index 1e894d34bdce..d8a6aecf99cb 100644
--- a/include/linux/page_idle.h
+++ b/include/linux/page_idle.h
@@ -6,7 +6,7 @@
#include <linux/page-flags.h>
#include <linux/page_ext.h>
-#ifdef CONFIG_IDLE_PAGE_TRACKING
+#ifdef CONFIG_PAGE_IDLE_FLAG
#ifdef CONFIG_64BIT
static inline bool page_is_young(struct page *page)
@@ -106,7 +106,7 @@ static inline void clear_page_idle(struct page *page)
}
#endif /* CONFIG_64BIT */
-#else /* !CONFIG_IDLE_PAGE_TRACKING */
+#else /* !CONFIG_PAGE_IDLE_FLAG */
static inline bool page_is_young(struct page *page)
{
@@ -135,6 +135,6 @@ static inline void clear_page_idle(struct page *page)
{
}
-#endif /* CONFIG_IDLE_PAGE_TRACKING */
+#endif /* CONFIG_PAGE_IDLE_FLAG */
#endif /* _LINUX_MM_PAGE_IDLE_H */
diff --git a/include/trace/events/mmflags.h b/include/trace/events/mmflags.h
index 5fb752034386..4d182c32071b 100644
--- a/include/trace/events/mmflags.h
+++ b/include/trace/events/mmflags.h
@@ -73,7 +73,7 @@
#define IF_HAVE_PG_HWPOISON(flag,string)
#endif
-#if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
+#if defined(CONFIG_PAGE_IDLE_FLAG) && defined(CONFIG_64BIT)
#define IF_HAVE_PG_IDLE(flag,string) ,{1UL << flag, string}
#else
#define IF_HAVE_PG_IDLE(flag,string)
diff --git a/mm/Kconfig b/mm/Kconfig
index a99d755d67d3..8b1dacc60a8e 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -765,10 +765,18 @@ config DEFERRED_STRUCT_PAGE_INIT
lifetime of the system until these kthreads finish the
initialisation.
+config PAGE_IDLE_FLAG
+ bool "Add PG_idle and PG_young flags"
+ help
+ This feature adds PG_idle and PG_young flags in 'struct page'. PTE
+ Accessed bit writers can set the state of the bit in the flags to let
+ other PTE Accessed bit readers don't disturbed.
+
config IDLE_PAGE_TRACKING
bool "Enable idle page tracking"
depends on SYSFS && MMU
select PAGE_EXTENSION if !64BIT
+ select PAGE_IDLE_FLAG
help
This feature allows to estimate the amount of user pages that have
not been touched during a given period of time. This information can
diff --git a/mm/page_ext.c b/mm/page_ext.c
index a3616f7a0e9e..f9a6ff65ac0a 100644
--- a/mm/page_ext.c
+++ b/mm/page_ext.c
@@ -58,11 +58,21 @@
* can utilize this callback to initialize the state of it correctly.
*/
+#if defined(CONFIG_PAGE_IDLE_FLAG) && !defined(CONFIG_64BIT)
+static bool need_page_idle(void)
+{
+ return true;
+}
+struct page_ext_operations page_idle_ops = {
+ .need = need_page_idle,
+};
+#endif
+
static struct page_ext_operations *page_ext_ops[] = {
#ifdef CONFIG_PAGE_OWNER
&page_owner_ops,
#endif
-#if defined(CONFIG_IDLE_PAGE_TRACKING) && !defined(CONFIG_64BIT)
+#if defined(CONFIG_PAGE_IDLE_FLAG) && !defined(CONFIG_64BIT)
&page_idle_ops,
#endif
};
diff --git a/mm/page_idle.c b/mm/page_idle.c
index 057c61df12db..144fb4ed961d 100644
--- a/mm/page_idle.c
+++ b/mm/page_idle.c
@@ -211,16 +211,6 @@ static const struct attribute_group page_idle_attr_group = {
.name = "page_idle",
};
-#ifndef CONFIG_64BIT
-static bool need_page_idle(void)
-{
- return true;
-}
-struct page_ext_operations page_idle_ops = {
- .need = need_page_idle,
-};
-#endif
-
static int __init page_idle_init(void)
{
int err;
--
2.17.1
From: SeongJae Park <[email protected]>
This commit introduces a reference implementation of the address space
specific low level primitives for the virtual address space, so that
users of DAMON can easily monitor the data accesses on virtual address
spaces of specific processes by simply configuring the implementation to
be used by DAMON.
The low level primitives for the fundamental access monitoring are
defined in two parts:
1. Identification of the monitoring target address range for the address
space.
2. Access check of specific address range in the target space.
The reference implementation for the virtual address space provided by
this commit is designed as below.
PTE Accessed-bit Based Access Check
-----------------------------------
The implementation uses PTE Accessed-bit for basic access checks. That
is, it clears the bit for next sampling target page and checks whether
it set again after one sampling period. This could disturb other kernel
subsystems using the Accessed bits, namely Idle page tracking and the
reclaim logic. To avoid such disturbances, DAMON makes it mutually
exclusive with Idle page tracking and uses ``PG_idle`` and ``PG_young``
page flags to solve the conflict with the reclaim logics, as Idle page
tracking does.
VMA-based Target Address Range Construction
-------------------------------------------
Only small parts in the super-huge virtual address space of the
processes are mapped to physical memory and accessed. Thus, tracking
the unmapped address regions is just wasteful. However, because DAMON
can deal with some level of noise using the adaptive regions adjustment
mechanism, tracking every mapping is not strictly required but could
even incur a high overhead in some cases. That said, too huge unmapped
areas inside the monitoring target should be removed to not take the
time for the adaptive mechanism.
For the reason, this implementation converts the complex mappings to
three distinct regions that cover every mapped area of the address
space. Also, the two gaps between the three regions are the two biggest
unmapped areas in the given address space. The two biggest unmapped
areas would be the gap between the heap and the uppermost mmap()-ed
region, and the gap between the lowermost mmap()-ed region and the stack
in most of the cases. Because these gaps are exceptionally huge in
usual address spacees, excluding these will be sufficient to make a
reasonable trade-off. Below shows this in detail::
<heap>
<BIG UNMAPPED REGION 1>
<uppermost mmap()-ed region>
(small mmap()-ed regions and munmap()-ed regions)
<lowermost mmap()-ed region>
<BIG UNMAPPED REGION 2>
<stack>
Signed-off-by: SeongJae Park <[email protected]>
Reviewed-by: Leonard Foerster <[email protected]>
---
include/linux/damon.h | 7 +
mm/Kconfig | 3 +
mm/damon.c | 542 ++++++++++++++++++++++++++++++++++++++++++
3 files changed, 552 insertions(+)
diff --git a/include/linux/damon.h b/include/linux/damon.h
index 6bd86bc47a74..f79112c56bbc 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -155,6 +155,13 @@ struct damon_ctx {
void (*aggregate_cb)(struct damon_ctx *context);
};
+/* Reference callback implementations for virtual memory */
+void kdamond_init_vm_regions(struct damon_ctx *ctx);
+void kdamond_update_vm_regions(struct damon_ctx *ctx);
+void kdamond_prepare_vm_access_checks(struct damon_ctx *ctx);
+unsigned int kdamond_check_vm_accesses(struct damon_ctx *ctx);
+bool kdamond_vm_target_valid(struct damon_target *t);
+
int damon_set_targets(struct damon_ctx *ctx,
unsigned long *ids, ssize_t nr_ids);
int damon_set_attrs(struct damon_ctx *ctx, unsigned long sample_int,
diff --git a/mm/Kconfig b/mm/Kconfig
index 8b1dacc60a8e..21cbd394bc78 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -882,6 +882,9 @@ config MAPPING_DIRTY_HELPERS
config DAMON
bool "Data Access Monitor"
+ depends on MMU && !IDLE_PAGE_TRACKING
+ select PAGE_EXTENSION if !64BIT
+ select PAGE_IDLE_FLAG
help
This feature allows to monitor access frequency of each memory
region. The information can be useful for performance-centric DRAM
diff --git a/mm/damon.c b/mm/damon.c
index 9183b22ab4c9..fa908dc39270 100644
--- a/mm/damon.c
+++ b/mm/damon.c
@@ -9,6 +9,10 @@
* This file is constructed in below parts.
*
* - Functions and macros for DAMON data structures
+ * - Functions for the initial monitoring target regions construction
+ * - Functions for the dynamic monitoring target regions update
+ * - Functions for the access checking of the regions
+ * - Functions for the target validity check
* - Functions for DAMON core logics and features
* - Functions for the DAMON programming interface
* - Functions for the initialization
@@ -20,6 +24,7 @@
#include <linux/delay.h>
#include <linux/kthread.h>
#include <linux/mm.h>
+#include <linux/mmu_notifier.h>
#include <linux/module.h>
#include <linux/page_idle.h>
#include <linux/random.h>
@@ -193,6 +198,543 @@ static unsigned long damon_region_sz_limit(struct damon_ctx *ctx)
return sz;
}
+/*
+ * Functions for the initial monitoring target regions construction
+ */
+
+/*
+ * 't->id' should be the pointer to the relevant 'struct pid' having reference
+ * count. Caller must put the returned task, unless it is NULL.
+ */
+#define damon_get_task_struct(t) \
+ (get_pid_task((struct pid *)t->id, PIDTYPE_PID))
+
+/*
+ * Get the mm_struct of the given target
+ *
+ * Caller _must_ put the mm_struct after use, unless it is NULL.
+ *
+ * Returns the mm_struct of the target on success, NULL on failure
+ */
+static struct mm_struct *damon_get_mm(struct damon_target *t)
+{
+ struct task_struct *task;
+ struct mm_struct *mm;
+
+ task = damon_get_task_struct(t);
+ if (!task)
+ return NULL;
+
+ mm = get_task_mm(task);
+ put_task_struct(task);
+ return mm;
+}
+
+/*
+ * Size-evenly split a region into 'nr_pieces' small regions
+ *
+ * Returns 0 on success, or negative error code otherwise.
+ */
+static int damon_split_region_evenly(struct damon_ctx *ctx,
+ struct damon_region *r, unsigned int nr_pieces)
+{
+ unsigned long sz_orig, sz_piece, orig_end;
+ struct damon_region *n = NULL, *next;
+ unsigned long start;
+
+ if (!r || !nr_pieces)
+ return -EINVAL;
+
+ orig_end = r->ar.end;
+ sz_orig = r->ar.end - r->ar.start;
+ sz_piece = ALIGN_DOWN(sz_orig / nr_pieces, MIN_REGION);
+
+ if (!sz_piece)
+ return -EINVAL;
+
+ r->ar.end = r->ar.start + sz_piece;
+ next = damon_next_region(r);
+ for (start = r->ar.end; start + sz_piece <= orig_end;
+ start += sz_piece) {
+ n = damon_new_region(start, start + sz_piece);
+ if (!n)
+ return -ENOMEM;
+ damon_insert_region(n, r, next);
+ r = n;
+ }
+ /* complement last region for possible rounding error */
+ if (n)
+ n->ar.end = orig_end;
+
+ return 0;
+}
+
+static unsigned long sz_range(struct damon_addr_range *r)
+{
+ return r->end - r->start;
+}
+
+static void swap_ranges(struct damon_addr_range *r1,
+ struct damon_addr_range *r2)
+{
+ struct damon_addr_range tmp;
+
+ tmp = *r1;
+ *r1 = *r2;
+ *r2 = tmp;
+}
+
+/*
+ * Find three regions separated by two biggest unmapped regions
+ *
+ * vma the head vma of the target address space
+ * regions an array of three address ranges that results will be saved
+ *
+ * This function receives an address space and finds three regions in it which
+ * separated by the two biggest unmapped regions in the space. Please refer to
+ * below comments of 'damon_init_vm_regions_of()' function to know why this is
+ * necessary.
+ *
+ * Returns 0 if success, or negative error code otherwise.
+ */
+static int damon_three_regions_in_vmas(struct vm_area_struct *vma,
+ struct damon_addr_range regions[3])
+{
+ struct damon_addr_range gap = {0}, first_gap = {0}, second_gap = {0};
+ struct vm_area_struct *last_vma = NULL;
+ unsigned long start = 0;
+ struct rb_root rbroot;
+
+ /* Find two biggest gaps so that first_gap > second_gap > others */
+ for (; vma; vma = vma->vm_next) {
+ if (!last_vma) {
+ start = vma->vm_start;
+ goto next;
+ }
+
+ if (vma->rb_subtree_gap <= sz_range(&second_gap)) {
+ rbroot.rb_node = &vma->vm_rb;
+ vma = rb_entry(rb_last(&rbroot),
+ struct vm_area_struct, vm_rb);
+ goto next;
+ }
+
+ gap.start = last_vma->vm_end;
+ gap.end = vma->vm_start;
+ if (sz_range(&gap) > sz_range(&second_gap)) {
+ swap_ranges(&gap, &second_gap);
+ if (sz_range(&second_gap) > sz_range(&first_gap))
+ swap_ranges(&second_gap, &first_gap);
+ }
+next:
+ last_vma = vma;
+ }
+
+ if (!sz_range(&second_gap) || !sz_range(&first_gap))
+ return -EINVAL;
+
+ /* Sort the two biggest gaps by address */
+ if (first_gap.start > second_gap.start)
+ swap_ranges(&first_gap, &second_gap);
+
+ /* Store the result */
+ regions[0].start = ALIGN(start, MIN_REGION);
+ regions[0].end = ALIGN(first_gap.start, MIN_REGION);
+ regions[1].start = ALIGN(first_gap.end, MIN_REGION);
+ regions[1].end = ALIGN(second_gap.start, MIN_REGION);
+ regions[2].start = ALIGN(second_gap.end, MIN_REGION);
+ regions[2].end = ALIGN(last_vma->vm_end, MIN_REGION);
+
+ return 0;
+}
+
+/*
+ * Get the three regions in the given target (task)
+ *
+ * Returns 0 on success, negative error code otherwise.
+ */
+static int damon_three_regions_of(struct damon_target *t,
+ struct damon_addr_range regions[3])
+{
+ struct mm_struct *mm;
+ int rc;
+
+ mm = damon_get_mm(t);
+ if (!mm)
+ return -EINVAL;
+
+ mmap_read_lock(mm);
+ rc = damon_three_regions_in_vmas(mm->mmap, regions);
+ mmap_read_unlock(mm);
+
+ mmput(mm);
+ return rc;
+}
+
+/*
+ * Initialize the monitoring target regions for the given target (task)
+ *
+ * t the given target
+ *
+ * Because only a number of small portions of the entire address space
+ * is actually mapped to the memory and accessed, monitoring the unmapped
+ * regions is wasteful. That said, because we can deal with small noises,
+ * tracking every mapping is not strictly required but could even incur a high
+ * overhead if the mapping frequently changes or the number of mappings is
+ * high. The adaptive regions adjustment mechanism will further help to deal
+ * with the noise by simply identifying the unmapped areas as a region that
+ * has no access. Moreover, applying the real mappings that would have many
+ * unmapped areas inside will make the adaptive mechanism quite complex. That
+ * said, too huge unmapped areas inside the monitoring target should be removed
+ * to not take the time for the adaptive mechanism.
+ *
+ * For the reason, we convert the complex mappings to three distinct regions
+ * that cover every mapped area of the address space. Also the two gaps
+ * between the three regions are the two biggest unmapped areas in the given
+ * address space. In detail, this function first identifies the start and the
+ * end of the mappings and the two biggest unmapped areas of the address space.
+ * Then, it constructs the three regions as below:
+ *
+ * [mappings[0]->start, big_two_unmapped_areas[0]->start)
+ * [big_two_unmapped_areas[0]->end, big_two_unmapped_areas[1]->start)
+ * [big_two_unmapped_areas[1]->end, mappings[nr_mappings - 1]->end)
+ *
+ * As usual memory map of processes is as below, the gap between the heap and
+ * the uppermost mmap()-ed region, and the gap between the lowermost mmap()-ed
+ * region and the stack will be two biggest unmapped regions. Because these
+ * gaps are exceptionally huge areas in usual address space, excluding these
+ * two biggest unmapped regions will be sufficient to make a trade-off.
+ *
+ * <heap>
+ * <BIG UNMAPPED REGION 1>
+ * <uppermost mmap()-ed region>
+ * (other mmap()-ed regions and small unmapped regions)
+ * <lowermost mmap()-ed region>
+ * <BIG UNMAPPED REGION 2>
+ * <stack>
+ */
+static void damon_init_vm_regions_of(struct damon_ctx *c,
+ struct damon_target *t)
+{
+ struct damon_region *r;
+ struct damon_addr_range regions[3];
+ unsigned long sz = 0, nr_pieces;
+ int i;
+
+ if (damon_three_regions_of(t, regions)) {
+ pr_err("Failed to get three regions of target %lu\n", t->id);
+ return;
+ }
+
+ for (i = 0; i < 3; i++)
+ sz += regions[i].end - regions[i].start;
+ if (c->min_nr_regions)
+ sz /= c->min_nr_regions;
+ if (sz < MIN_REGION)
+ sz = MIN_REGION;
+
+ /* Set the initial three regions of the target */
+ for (i = 0; i < 3; i++) {
+ r = damon_new_region(regions[i].start, regions[i].end);
+ if (!r) {
+ pr_err("%d'th init region creation failed\n", i);
+ return;
+ }
+ damon_add_region(r, t);
+
+ nr_pieces = (regions[i].end - regions[i].start) / sz;
+ damon_split_region_evenly(c, r, nr_pieces);
+ }
+}
+
+/* Initialize '->regions_list' of every target (task) */
+void kdamond_init_vm_regions(struct damon_ctx *ctx)
+{
+ struct damon_target *t;
+
+ damon_for_each_target(t, ctx) {
+ /* the user may set the target regions as they want */
+ if (!nr_damon_regions(t))
+ damon_init_vm_regions_of(ctx, t);
+ }
+}
+
+/*
+ * Functions for the dynamic monitoring target regions update
+ */
+
+/*
+ * Check whether a region is intersecting an address range
+ *
+ * Returns true if it is.
+ */
+static bool damon_intersect(struct damon_region *r, struct damon_addr_range *re)
+{
+ return !(r->ar.end <= re->start || re->end <= r->ar.start);
+}
+
+/*
+ * Update damon regions for the three big regions of the given target
+ *
+ * t the given target
+ * bregions the three big regions of the target
+ */
+static void damon_apply_three_regions(struct damon_ctx *ctx,
+ struct damon_target *t, struct damon_addr_range bregions[3])
+{
+ struct damon_region *r, *next;
+ unsigned int i = 0;
+
+ /* Remove regions which are not in the three big regions now */
+ damon_for_each_region_safe(r, next, t) {
+ for (i = 0; i < 3; i++) {
+ if (damon_intersect(r, &bregions[i]))
+ break;
+ }
+ if (i == 3)
+ damon_destroy_region(r);
+ }
+
+ /* Adjust intersecting regions to fit with the three big regions */
+ for (i = 0; i < 3; i++) {
+ struct damon_region *first = NULL, *last;
+ struct damon_region *newr;
+ struct damon_addr_range *br;
+
+ br = &bregions[i];
+ /* Get the first and last regions which intersects with br */
+ damon_for_each_region(r, t) {
+ if (damon_intersect(r, br)) {
+ if (!first)
+ first = r;
+ last = r;
+ }
+ if (r->ar.start >= br->end)
+ break;
+ }
+ if (!first) {
+ /* no damon_region intersects with this big region */
+ newr = damon_new_region(
+ ALIGN_DOWN(br->start, MIN_REGION),
+ ALIGN(br->end, MIN_REGION));
+ if (!newr)
+ continue;
+ damon_insert_region(newr, damon_prev_region(r), r);
+ } else {
+ first->ar.start = ALIGN_DOWN(br->start, MIN_REGION);
+ last->ar.end = ALIGN(br->end, MIN_REGION);
+ }
+ }
+}
+
+/*
+ * Update regions for current memory mappings
+ */
+void kdamond_update_vm_regions(struct damon_ctx *ctx)
+{
+ struct damon_addr_range three_regions[3];
+ struct damon_target *t;
+
+ damon_for_each_target(t, ctx) {
+ if (damon_three_regions_of(t, three_regions))
+ continue;
+ damon_apply_three_regions(ctx, t, three_regions);
+ }
+}
+
+/*
+ * Functions for the access checking of the regions
+ */
+
+static void damon_ptep_mkold(pte_t *pte, struct mm_struct *mm,
+ unsigned long addr)
+{
+ bool referenced = false;
+ struct page *page = pte_page(*pte);
+
+ if (pte_young(*pte)) {
+ referenced = true;
+ *pte = pte_mkold(*pte);
+ }
+
+#ifdef CONFIG_MMU_NOTIFIER
+ if (mmu_notifier_clear_young(mm, addr, addr + PAGE_SIZE))
+ referenced = true;
+#endif /* CONFIG_MMU_NOTIFIER */
+
+ if (referenced)
+ set_page_young(page);
+
+ set_page_idle(page);
+}
+
+static void damon_pmdp_mkold(pmd_t *pmd, struct mm_struct *mm,
+ unsigned long addr)
+{
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+ bool referenced = false;
+ struct page *page = pmd_page(*pmd);
+
+ if (pmd_young(*pmd)) {
+ referenced = true;
+ *pmd = pmd_mkold(*pmd);
+ }
+
+#ifdef CONFIG_MMU_NOTIFIER
+ if (mmu_notifier_clear_young(mm, addr,
+ addr + ((1UL) << HPAGE_PMD_SHIFT)))
+ referenced = true;
+#endif /* CONFIG_MMU_NOTIFIER */
+
+ if (referenced)
+ set_page_young(page);
+
+ set_page_idle(page);
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+}
+
+static void damon_mkold(struct mm_struct *mm, unsigned long addr)
+{
+ pte_t *pte = NULL;
+ pmd_t *pmd = NULL;
+ spinlock_t *ptl;
+
+ if (follow_pte_pmd(mm, addr, NULL, &pte, &pmd, &ptl))
+ return;
+
+ if (pte) {
+ damon_ptep_mkold(pte, mm, addr);
+ pte_unmap_unlock(pte, ptl);
+ } else {
+ damon_pmdp_mkold(pmd, mm, addr);
+ spin_unlock(ptl);
+ }
+}
+
+static void damon_prepare_vm_access_check(struct damon_ctx *ctx,
+ struct mm_struct *mm, struct damon_region *r)
+{
+ r->sampling_addr = damon_rand(r->ar.start, r->ar.end);
+
+ damon_mkold(mm, r->sampling_addr);
+}
+
+void kdamond_prepare_vm_access_checks(struct damon_ctx *ctx)
+{
+ struct damon_target *t;
+ struct mm_struct *mm;
+ struct damon_region *r;
+
+ damon_for_each_target(t, ctx) {
+ mm = damon_get_mm(t);
+ if (!mm)
+ continue;
+ damon_for_each_region(r, t)
+ damon_prepare_vm_access_check(ctx, mm, r);
+ mmput(mm);
+ }
+}
+
+static bool damon_young(struct mm_struct *mm, unsigned long addr,
+ unsigned long *page_sz)
+{
+ pte_t *pte = NULL;
+ pmd_t *pmd = NULL;
+ spinlock_t *ptl;
+ bool young = false;
+
+ if (follow_pte_pmd(mm, addr, NULL, &pte, &pmd, &ptl))
+ return false;
+
+ *page_sz = PAGE_SIZE;
+ if (pte) {
+ young = pte_young(*pte);
+ if (!young)
+ young = !page_is_idle(pte_page(*pte));
+ pte_unmap_unlock(pte, ptl);
+ return young;
+ }
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+ young = pmd_young(*pmd);
+ if (!young)
+ young = !page_is_idle(pmd_page(*pmd));
+ spin_unlock(ptl);
+ *page_sz = ((1UL) << HPAGE_PMD_SHIFT);
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+
+ return young;
+}
+
+/*
+ * Check whether the region was accessed after the last preparation
+ *
+ * mm 'mm_struct' for the given virtual address space
+ * r the region to be checked
+ */
+static void damon_check_vm_access(struct damon_ctx *ctx,
+ struct mm_struct *mm, struct damon_region *r)
+{
+ static struct mm_struct *last_mm;
+ static unsigned long last_addr;
+ static unsigned long last_page_sz = PAGE_SIZE;
+ static bool last_accessed;
+
+ /* If the region is in the last checked page, reuse the result */
+ if (mm == last_mm && (ALIGN_DOWN(last_addr, last_page_sz) ==
+ ALIGN_DOWN(r->sampling_addr, last_page_sz))) {
+ if (last_accessed)
+ r->nr_accesses++;
+ return;
+ }
+
+ last_accessed = damon_young(mm, r->sampling_addr, &last_page_sz);
+ if (last_accessed)
+ r->nr_accesses++;
+
+ last_mm = mm;
+ last_addr = r->sampling_addr;
+}
+
+unsigned int kdamond_check_vm_accesses(struct damon_ctx *ctx)
+{
+ struct damon_target *t;
+ struct mm_struct *mm;
+ struct damon_region *r;
+ unsigned int max_nr_accesses = 0;
+
+ damon_for_each_target(t, ctx) {
+ mm = damon_get_mm(t);
+ if (!mm)
+ continue;
+ damon_for_each_region(r, t) {
+ damon_check_vm_access(ctx, mm, r);
+ max_nr_accesses = max(r->nr_accesses, max_nr_accesses);
+ }
+ mmput(mm);
+ }
+
+ return max_nr_accesses;
+}
+
+
+/*
+ * Functions for the target validity check
+ */
+
+bool kdamond_vm_target_valid(struct damon_target *t)
+{
+ struct task_struct *task;
+
+ task = damon_get_task_struct(t);
+ if (task) {
+ put_task_struct(task);
+ return true;
+ }
+
+ return false;
+}
+
/*
* Functions for DAMON core logics and features
*/
--
2.17.1
From: SeongJae Park <[email protected]>
This commit implements the recording feature of DAMON. If this feature
is enabled, DAMON writes the monitored access patterns in its binary
format into a file which specified by the user. This is already able to
be implemented by each user using the callbacks. However, as the
recording is expected to be widely used, this commit implements the
feature in the DAMON, for more convenience.
Signed-off-by: SeongJae Park <[email protected]>
Reviewed-by: Leonard Foerster <[email protected]>
---
include/linux/damon.h | 15 +++++
mm/damon.c | 141 +++++++++++++++++++++++++++++++++++++++++-
2 files changed, 153 insertions(+), 3 deletions(-)
diff --git a/include/linux/damon.h b/include/linux/damon.h
index f79112c56bbc..ad771c39d1a9 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -75,6 +75,14 @@ struct damon_target {
* in case of virtual memory monitoring) and applies the changes for each
* @regions_update_interval. All time intervals are in micro-seconds.
*
+ * @rbuf: In-memory buffer for monitoring result recording.
+ * @rbuf_len: The length of @rbuf.
+ * @rbuf_offset: The offset for next write to @rbuf.
+ * @rfile_path: Record file path.
+ *
+ * If @rbuf, @rbuf_len, and @rfile_path are set, the monitored results are
+ * automatically stored in @rfile_path file.
+ *
* @kdamond: Kernel thread who does the monitoring.
* @kdamond_stop: Notifies whether kdamond should stop.
* @kdamond_lock: Mutex for the synchronizations with @kdamond.
@@ -139,6 +147,11 @@ struct damon_ctx {
struct timespec64 last_aggregation;
struct timespec64 last_regions_update;
+ unsigned char *rbuf;
+ unsigned int rbuf_len;
+ unsigned int rbuf_offset;
+ char *rfile_path;
+
struct task_struct *kdamond;
bool kdamond_stop;
struct mutex kdamond_lock;
@@ -167,6 +180,8 @@ int damon_set_targets(struct damon_ctx *ctx,
int damon_set_attrs(struct damon_ctx *ctx, unsigned long sample_int,
unsigned long aggr_int, unsigned long regions_update_int,
unsigned long min_nr_reg, unsigned long max_nr_reg);
+int damon_set_recording(struct damon_ctx *ctx,
+ unsigned int rbuf_len, char *rfile_path);
int damon_start(struct damon_ctx *ctx);
int damon_stop(struct damon_ctx *ctx);
diff --git a/mm/damon.c b/mm/damon.c
index fa908dc39270..b3420ba97fd2 100644
--- a/mm/damon.c
+++ b/mm/damon.c
@@ -57,6 +57,10 @@
#define damon_for_each_target_safe(t, next, ctx) \
list_for_each_entry_safe(t, next, &(ctx)->targets_list, list)
+#define MIN_RECORD_BUFFER_LEN 1024
+#define MAX_RECORD_BUFFER_LEN (4 * 1024 * 1024)
+#define MAX_RFILE_PATH_LEN 256
+
/* Get a random number in [l, r) */
#define damon_rand(l, r) (l + prandom_u32() % (r - l))
@@ -772,16 +776,88 @@ static bool kdamond_aggregate_interval_passed(struct damon_ctx *ctx)
}
/*
- * Reset the aggregated monitoring results
+ * Flush the content in the result buffer to the result file
+ */
+static void damon_flush_rbuffer(struct damon_ctx *ctx)
+{
+ ssize_t sz;
+ loff_t pos = 0;
+ struct file *rfile;
+
+ if (!ctx->rbuf_offset)
+ return;
+
+ rfile = filp_open(ctx->rfile_path, O_CREAT | O_RDWR | O_APPEND, 0644);
+ if (IS_ERR(rfile)) {
+ pr_err("Cannot open the result file %s\n",
+ ctx->rfile_path);
+ return;
+ }
+
+ while (ctx->rbuf_offset) {
+ sz = kernel_write(rfile, ctx->rbuf, ctx->rbuf_offset, &pos);
+ if (sz < 0)
+ break;
+ ctx->rbuf_offset -= sz;
+ }
+ filp_close(rfile, NULL);
+}
+
+/*
+ * Write a data into the result buffer
+ */
+static void damon_write_rbuf(struct damon_ctx *ctx, void *data, ssize_t size)
+{
+ if (!ctx->rbuf_len || !ctx->rbuf || !ctx->rfile_path)
+ return;
+ if (ctx->rbuf_offset + size > ctx->rbuf_len)
+ damon_flush_rbuffer(ctx);
+ if (ctx->rbuf_offset + size > ctx->rbuf_len) {
+ pr_warn("%s: flush failed, or wrong size given(%u, %zu)\n",
+ __func__, ctx->rbuf_offset, size);
+ return;
+ }
+
+ memcpy(&ctx->rbuf[ctx->rbuf_offset], data, size);
+ ctx->rbuf_offset += size;
+}
+
+/*
+ * Flush the aggregated monitoring results to the result buffer
+ *
+ * Stores current tracking results to the result buffer and reset 'nr_accesses'
+ * of each region. The format for the result buffer is as below:
+ *
+ * <time> <number of targets> <array of target infos>
+ *
+ * target info: <id> <number of regions> <array of region infos>
+ * region info: <start address> <end address> <nr_accesses>
*/
static void kdamond_reset_aggregated(struct damon_ctx *c)
{
struct damon_target *t;
- struct damon_region *r;
+ struct timespec64 now;
+ unsigned int nr;
+
+ ktime_get_coarse_ts64(&now);
+
+ damon_write_rbuf(c, &now, sizeof(now));
+ nr = nr_damon_targets(c);
+ damon_write_rbuf(c, &nr, sizeof(nr));
damon_for_each_target(t, c) {
- damon_for_each_region(r, t)
+ struct damon_region *r;
+
+ damon_write_rbuf(c, &t->id, sizeof(t->id));
+ nr = nr_damon_regions(t);
+ damon_write_rbuf(c, &nr, sizeof(nr));
+ damon_for_each_region(r, t) {
+ damon_write_rbuf(c, &r->ar.start, sizeof(r->ar.start));
+ damon_write_rbuf(c, &r->ar.end, sizeof(r->ar.end));
+ damon_write_rbuf(c, &r->nr_accesses,
+ sizeof(r->nr_accesses));
r->nr_accesses = 0;
+ }
}
}
@@ -965,6 +1041,14 @@ static bool kdamond_need_stop(struct damon_ctx *ctx)
return true;
}
+static void kdamond_write_record_header(struct damon_ctx *ctx)
+{
+ int recfmt_ver = 2;
+
+ damon_write_rbuf(ctx, "damon_recfmt_ver", 16);
+ damon_write_rbuf(ctx, &recfmt_ver, sizeof(recfmt_ver));
+}
+
/*
* The monitoring daemon that runs as a kernel thread
*/
@@ -981,6 +1065,8 @@ static int kdamond_fn(void *data)
ctx->init_target_regions(ctx);
sz_limit = damon_region_sz_limit(ctx);
+ kdamond_write_record_header(ctx);
+
while (!kdamond_need_stop(ctx)) {
if (ctx->prepare_access_checks)
ctx->prepare_access_checks(ctx);
@@ -1007,6 +1093,7 @@ static int kdamond_fn(void *data)
sz_limit = damon_region_sz_limit(ctx);
}
}
+ damon_flush_rbuffer(ctx);
damon_for_each_target(t, ctx) {
damon_for_each_region_safe(r, next, t)
damon_destroy_region(r);
@@ -1112,6 +1199,54 @@ int damon_set_targets(struct damon_ctx *ctx,
return 0;
}
+/**
+ * damon_set_recording() - Set attributes for the recording.
+ * @ctx: target kdamond context
+ * @rbuf_len: length of the result buffer
+ * @rfile_path: path to the monitor result files
+ *
+ * Setting 'rbuf_len' 0 disables recording.
+ *
+ * This function should not be called while the kdamond is running.
+ *
+ * Return: 0 on success, negative error code otherwise.
+ */
+int damon_set_recording(struct damon_ctx *ctx,
+ unsigned int rbuf_len, char *rfile_path)
+{
+ size_t rfile_path_len;
+
+ if (rbuf_len && (rbuf_len > MAX_RECORD_BUFFER_LEN ||
+ rbuf_len < MIN_RECORD_BUFFER_LEN)) {
+ pr_err("result buffer size (%u) is out of [%d,%d]\n",
+ rbuf_len, MIN_RECORD_BUFFER_LEN,
+ MAX_RECORD_BUFFER_LEN);
+ return -EINVAL;
+ }
+ rfile_path_len = strnlen(rfile_path, MAX_RFILE_PATH_LEN);
+ if (rfile_path_len >= MAX_RFILE_PATH_LEN) {
+ pr_err("too long (>%d) result file path %s\n",
+ MAX_RFILE_PATH_LEN, rfile_path);
+ return -EINVAL;
+ }
+ ctx->rbuf_len = rbuf_len;
+ kfree(ctx->rbuf);
+ ctx->rbuf = NULL;
+ kfree(ctx->rfile_path);
+ ctx->rfile_path = NULL;
+
+ if (rbuf_len) {
+ ctx->rbuf = kvmalloc(rbuf_len, GFP_KERNEL);
+ if (!ctx->rbuf)
+ return -ENOMEM;
+ }
+ ctx->rfile_path = kmalloc(rfile_path_len + 1, GFP_KERNEL);
+ if (!ctx->rfile_path)
+ return -ENOMEM;
+ strncpy(ctx->rfile_path, rfile_path, rfile_path_len + 1);
+ return 0;
+}
+
/**
* damon_set_attrs() - Set attributes for the monitoring.
* @ctx: monitoring context
--
2.17.1
From: SeongJae Park <[email protected]>
The monitoring target address range can be dynamically changed. For
example, virtual memory could be dynamically mapped and unmapped.
Physical memory could be hot-plugged.
As the changes could be quite frequent in some cases, DAMON checks the
dynamic memory mapping changes and applies it to the abstracted target
area only for each of a user-specified time interval, ``regions update
interval``.
Signed-off-by: SeongJae Park <[email protected]>
Reviewed-by: Leonard Foerster <[email protected]>
---
include/linux/damon.h | 20 +++++++++++++++-----
mm/damon.c | 23 +++++++++++++++++++++--
2 files changed, 36 insertions(+), 7 deletions(-)
diff --git a/include/linux/damon.h b/include/linux/damon.h
index 84a959360f58..6bd86bc47a74 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -64,13 +64,16 @@ struct damon_target {
*
* @sample_interval: The time between access samplings.
* @aggr_interval: The time between monitor results aggregations.
+ * @regions_update_interval: The time between monitor regions updates.
* @min_nr_regions: The minimum number of monitoring regions.
* @max_nr_regions: The maximum number of monitoring regions.
*
* For each @sample_interval, DAMON checks whether each region is accessed or
* not. It aggregates and keeps the access information (number of accesses to
- * each region) for @aggr_interval time. All time intervals are in
- * micro-seconds.
+ * each region) for @aggr_interval time. DAMON also checks whether the target
+ * memory regions need update (e.g., by ``mmap()`` calls from the application,
+ * in case of virtual memory monitoring) and applies the changes for each
+ * @regions_update_interval. All time intervals are in micro-seconds.
*
* @kdamond: Kernel thread who does the monitoring.
* @kdamond_stop: Notifies whether kdamond should stop.
@@ -94,6 +97,7 @@ struct damon_target {
* @targets_list: Head of monitoring targets (&damon_target) list.
*
* @init_target_regions: Constructs initial monitoring target regions.
+ * @update_target_regions: Updates monitoring target regions.
* @prepare_access_checks: Prepares next access check of target regions.
* @check_accesses: Checks the access of target regions.
* @target_valid: Determine if the target is valid.
@@ -103,12 +107,15 @@ struct damon_target {
* DAMON can be extended for various address spaces by users. For this, users
* can register the target address space dependent low level functions for
* their usecases via the callback pointers of the context. The monitoring
- * thread calls @init_target_regions before starting the monitoring, and
+ * thread calls @init_target_regions before starting the monitoring,
+ * @update_target_regions for each @regions_update_interval, and
* @prepare_access_checks, @check_accesses, and @target_valid for each
* @sample_interval.
*
* @init_target_regions should construct proper monitoring target regions and
* link those to the DAMON context struct.
+ * @update_target_regions should update the monitoring target regions for
+ * current status.
* @prepare_access_checks should manipulate the monitoring regions to be
* prepare for the next access check.
* @check_accesses should check the accesses to each region that made after the
@@ -125,10 +132,12 @@ struct damon_target {
struct damon_ctx {
unsigned long sample_interval;
unsigned long aggr_interval;
+ unsigned long regions_update_interval;
unsigned long min_nr_regions;
unsigned long max_nr_regions;
struct timespec64 last_aggregation;
+ struct timespec64 last_regions_update;
struct task_struct *kdamond;
bool kdamond_stop;
@@ -138,6 +147,7 @@ struct damon_ctx {
/* callbacks */
void (*init_target_regions)(struct damon_ctx *context);
+ void (*update_target_regions)(struct damon_ctx *context);
void (*prepare_access_checks)(struct damon_ctx *context);
unsigned int (*check_accesses)(struct damon_ctx *context);
bool (*target_valid)(struct damon_target *target);
@@ -147,8 +157,8 @@ struct damon_ctx {
int damon_set_targets(struct damon_ctx *ctx,
unsigned long *ids, ssize_t nr_ids);
-int damon_set_attrs(struct damon_ctx *ctx,
- unsigned long sample_int, unsigned long aggr_int,
+int damon_set_attrs(struct damon_ctx *ctx, unsigned long sample_int,
+ unsigned long aggr_int, unsigned long regions_update_int,
unsigned long min_nr_reg, unsigned long max_nr_reg);
int damon_start(struct damon_ctx *ctx);
int damon_stop(struct damon_ctx *ctx);
diff --git a/mm/damon.c b/mm/damon.c
index 0b1000e11121..9183b22ab4c9 100644
--- a/mm/damon.c
+++ b/mm/damon.c
@@ -382,6 +382,17 @@ static void kdamond_split_regions(struct damon_ctx *ctx)
last_nr_regions = nr_regions;
}
+/*
+ * Check whether it is time to check and apply the target monitoring regions
+ *
+ * Returns true if it is.
+ */
+static bool kdamond_need_update_regions(struct damon_ctx *ctx)
+{
+ return damon_check_reset_time_interval(&ctx->last_regions_update,
+ ctx->regions_update_interval);
+}
+
/*
* Check whether current monitoring should be stopped
*
@@ -447,6 +458,12 @@ static int kdamond_fn(void *data)
kdamond_reset_aggregated(ctx);
kdamond_split_regions(ctx);
}
+
+ if (kdamond_need_update_regions(ctx)) {
+ if (ctx->update_target_regions)
+ ctx->update_target_regions(ctx);
+ sz_limit = damon_region_sz_limit(ctx);
+ }
}
damon_for_each_target(t, ctx) {
damon_for_each_region_safe(r, next, t)
@@ -557,6 +574,7 @@ int damon_set_targets(struct damon_ctx *ctx,
* damon_set_attrs() - Set attributes for the monitoring.
* @ctx: monitoring context
* @sample_int: time interval between samplings
+ * @regions_update_int: time interval between target regions update
* @aggr_int: time interval between aggregations
* @min_nr_reg: minimal number of regions
* @max_nr_reg: maximum number of regions
@@ -566,8 +584,8 @@ int damon_set_targets(struct damon_ctx *ctx,
*
* Return: 0 on success, negative error code otherwise.
*/
-int damon_set_attrs(struct damon_ctx *ctx,
- unsigned long sample_int, unsigned long aggr_int,
+int damon_set_attrs(struct damon_ctx *ctx, unsigned long sample_int,
+ unsigned long aggr_int, unsigned long regions_update_int,
unsigned long min_nr_reg, unsigned long max_nr_reg)
{
if (min_nr_reg < 3) {
@@ -583,6 +601,7 @@ int damon_set_attrs(struct damon_ctx *ctx,
ctx->sample_interval = sample_int;
ctx->aggr_interval = aggr_int;
+ ctx->regions_update_interval = regions_update_int;
ctx->min_nr_regions = min_nr_reg;
ctx->max_nr_regions = max_nr_reg;
--
2.17.1
From: SeongJae Park <[email protected]>
Even somehow the initial monitoring target regions are well constructed
to fulfill the assumption (pages in same region have similar access
frequencies), the data access pattern can be dynamically changed. This
will result in low monitoring quality. To keep the assumption as much
as possible, DAMON adaptively merges and splits each region based on
their access frequency.
For each ``aggregation interval``, it compares the access frequencies of
adjacent regions and merges those if the frequency difference is small.
Then, after it reports and clears the aggregated access frequency of
each region, it splits each region into two or three regions if the
total number of regions will not exceed the user-specified maximum
number of regions after the split.
In this way, DAMON provides its best-effort quality and minimal overhead
while keeping the upper-bound overhead that users set.
Signed-off-by: SeongJae Park <[email protected]>
Reviewed-by: Leonard Foerster <[email protected]>
---
include/linux/damon.h | 11 ++-
mm/damon.c | 191 ++++++++++++++++++++++++++++++++++++++++--
2 files changed, 189 insertions(+), 13 deletions(-)
diff --git a/include/linux/damon.h b/include/linux/damon.h
index 0b1153971e6d..84a959360f58 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -64,7 +64,8 @@ struct damon_target {
*
* @sample_interval: The time between access samplings.
* @aggr_interval: The time between monitor results aggregations.
- * @nr_regions: The number of monitoring regions.
+ * @min_nr_regions: The minimum number of monitoring regions.
+ * @max_nr_regions: The maximum number of monitoring regions.
*
* For each @sample_interval, DAMON checks whether each region is accessed or
* not. It aggregates and keeps the access information (number of accesses to
@@ -124,7 +125,8 @@ struct damon_target {
struct damon_ctx {
unsigned long sample_interval;
unsigned long aggr_interval;
- unsigned long nr_regions;
+ unsigned long min_nr_regions;
+ unsigned long max_nr_regions;
struct timespec64 last_aggregation;
@@ -145,8 +147,9 @@ struct damon_ctx {
int damon_set_targets(struct damon_ctx *ctx,
unsigned long *ids, ssize_t nr_ids);
-int damon_set_attrs(struct damon_ctx *ctx, unsigned long sample_int,
- unsigned long aggr_int, unsigned long min_nr_reg);
+int damon_set_attrs(struct damon_ctx *ctx,
+ unsigned long sample_int, unsigned long aggr_int,
+ unsigned long min_nr_reg, unsigned long max_nr_reg);
int damon_start(struct damon_ctx *ctx);
int damon_stop(struct damon_ctx *ctx);
diff --git a/mm/damon.c b/mm/damon.c
index 63e434ab483f..0b1000e11121 100644
--- a/mm/damon.c
+++ b/mm/damon.c
@@ -173,6 +173,26 @@ static unsigned int nr_damon_regions(struct damon_target *t)
return nr_regions;
}
+/* Returns the size upper limit for each monitoring region */
+static unsigned long damon_region_sz_limit(struct damon_ctx *ctx)
+{
+ struct damon_target *t;
+ struct damon_region *r;
+ unsigned long sz = 0;
+
+ damon_for_each_target(t, ctx) {
+ damon_for_each_region(r, t)
+ sz += r->ar.end - r->ar.start;
+ }
+
+ if (ctx->min_nr_regions)
+ sz /= ctx->min_nr_regions;
+ if (sz < MIN_REGION)
+ sz = MIN_REGION;
+
+ return sz;
+}
+
/*
* Functions for DAMON core logics and features
*/
@@ -223,6 +243,145 @@ static void kdamond_reset_aggregated(struct damon_ctx *c)
}
}
+#define sz_damon_region(r) (r->ar.end - r->ar.start)
+
+/*
+ * Merge two adjacent regions into one region
+ */
+static void damon_merge_two_regions(struct damon_region *l,
+ struct damon_region *r)
+{
+ l->nr_accesses = (l->nr_accesses * sz_damon_region(l) +
+ r->nr_accesses * sz_damon_region(r)) /
+ (sz_damon_region(l) + sz_damon_region(r));
+ l->ar.end = r->ar.end;
+ damon_destroy_region(r);
+}
+
+#define diff_of(a, b) (a > b ? a - b : b - a)
+
+/*
+ * Merge adjacent regions having similar access frequencies
+ *
+ * t target affected by this merge operation
+ * thres '->nr_accesses' diff threshold for the merge
+ * sz_limit size upper limit of each region
+ */
+static void damon_merge_regions_of(struct damon_target *t, unsigned int thres,
+ unsigned long sz_limit)
+{
+ struct damon_region *r, *prev = NULL, *next;
+
+ damon_for_each_region_safe(r, next, t) {
+ if (prev && prev->ar.end == r->ar.start &&
+ diff_of(prev->nr_accesses, r->nr_accesses) <= thres &&
+ sz_damon_region(prev) + sz_damon_region(r) <= sz_limit)
+ damon_merge_two_regions(prev, r);
+ else
+ prev = r;
+ }
+}
+
+/*
+ * Merge adjacent regions having similar access frequencies
+ *
+ * threshold '->nr_accesses' diff threshold for the merge
+ * sz_limit size upper limit of each region
+ *
+ * This function merges monitoring target regions which are adjacent and their
+ * access frequencies are similar. This is for minimizing the monitoring
+ * overhead under the dynamically changeable access pattern. If a merge was
+ * unnecessarily made, later 'kdamond_split_regions()' will revert it.
+ */
+static void kdamond_merge_regions(struct damon_ctx *c, unsigned int threshold,
+ unsigned long sz_limit)
+{
+ struct damon_target *t;
+
+ damon_for_each_target(t, c)
+ damon_merge_regions_of(t, threshold, sz_limit);
+}
+
+/*
+ * Split a region in two
+ *
+ * r the region to be split
+ * sz_r size of the first sub-region that will be made
+ */
+static void damon_split_region_at(struct damon_ctx *ctx,
+ struct damon_region *r, unsigned long sz_r)
+{
+ struct damon_region *new;
+
+ new = damon_new_region(r->ar.start + sz_r, r->ar.end);
+ r->ar.end = new->ar.start;
+
+ damon_insert_region(new, r, damon_next_region(r));
+}
+
+/* Split every region in the given target into 'nr_subs' regions */
+static void damon_split_regions_of(struct damon_ctx *ctx,
+ struct damon_target *t, int nr_subs)
+{
+ struct damon_region *r, *next;
+ unsigned long sz_region, sz_sub = 0;
+ int i;
+
+ damon_for_each_region_safe(r, next, t) {
+ sz_region = r->ar.end - r->ar.start;
+
+ for (i = 0; i < nr_subs - 1 &&
+ sz_region > 2 * MIN_REGION; i++) {
+ /*
+ * Randomly select size of left sub-region to be at
+ * least 10 percent and at most 90% of original region
+ */
+ sz_sub = ALIGN_DOWN(damon_rand(1, 10) *
+ sz_region / 10, MIN_REGION);
+ /* Do not allow blank region */
+ if (sz_sub == 0 || sz_sub >= sz_region)
+ continue;
+
+ damon_split_region_at(ctx, r, sz_sub);
+ sz_region = sz_sub;
+ }
+ }
+}
+
+/*
+ * Split every target region into randomly-sized small regions
+ *
+ * This function splits every target region into random-sized small regions if
+ * current total number of the regions is equal or smaller than half of the
+ * user-specified maximum number of regions. This is for maximizing the
+ * monitoring accuracy under the dynamically changeable access patterns. If a
+ * split was unnecessarily made, later 'kdamond_merge_regions()' will revert
+ * it.
+ */
+static void kdamond_split_regions(struct damon_ctx *ctx)
+{
+ struct damon_target *t;
+ unsigned int nr_regions = 0;
+ static unsigned int last_nr_regions;
+ int nr_subregions = 2;
+
+ damon_for_each_target(t, ctx)
+ nr_regions += nr_damon_regions(t);
+
+ if (nr_regions > ctx->max_nr_regions / 2)
+ return;
+
+ /* Maybe the middle of the region has different access frequency */
+ if (last_nr_regions == nr_regions &&
+ nr_regions < ctx->max_nr_regions / 3)
+ nr_subregions = 3;
+
+ damon_for_each_target(t, ctx)
+ damon_split_regions_of(ctx, t, nr_subregions);
+
+ last_nr_regions = nr_regions;
+}
+
/*
* Check whether current monitoring should be stopped
*
@@ -261,10 +420,14 @@ static int kdamond_fn(void *data)
struct damon_ctx *ctx = (struct damon_ctx *)data;
struct damon_target *t;
struct damon_region *r, *next;
+ unsigned int max_nr_accesses = 0;
+ unsigned long sz_limit = 0;
pr_info("kdamond (%d) starts\n", ctx->kdamond->pid);
if (ctx->init_target_regions)
ctx->init_target_regions(ctx);
+ sz_limit = damon_region_sz_limit(ctx);
+
while (!kdamond_need_stop(ctx)) {
if (ctx->prepare_access_checks)
ctx->prepare_access_checks(ctx);
@@ -274,14 +437,16 @@ static int kdamond_fn(void *data)
usleep_range(ctx->sample_interval, ctx->sample_interval + 1);
if (ctx->check_accesses)
- ctx->check_accesses(ctx);
+ max_nr_accesses = ctx->check_accesses(ctx);
if (kdamond_aggregate_interval_passed(ctx)) {
if (ctx->aggregate_cb)
ctx->aggregate_cb(ctx);
+ kdamond_merge_regions(ctx, max_nr_accesses / 10,
+ sz_limit);
kdamond_reset_aggregated(ctx);
+ kdamond_split_regions(ctx);
}
-
}
damon_for_each_target(t, ctx) {
damon_for_each_region_safe(r, next, t)
@@ -393,25 +558,33 @@ int damon_set_targets(struct damon_ctx *ctx,
* @ctx: monitoring context
* @sample_int: time interval between samplings
* @aggr_int: time interval between aggregations
- * @nr_reg: number of regions
+ * @min_nr_reg: minimal number of regions
+ * @max_nr_reg: maximum number of regions
*
* This function should not be called while the kdamond is running.
* Every time interval is in micro-seconds.
*
* Return: 0 on success, negative error code otherwise.
*/
-int damon_set_attrs(struct damon_ctx *ctx, unsigned long sample_int,
- unsigned long aggr_int, unsigned long nr_reg)
+int damon_set_attrs(struct damon_ctx *ctx,
+ unsigned long sample_int, unsigned long aggr_int,
+ unsigned long min_nr_reg, unsigned long max_nr_reg)
{
- if (nr_reg < 3) {
- pr_err("nr_regions (%lu) must be at least 3\n",
- nr_reg);
+ if (min_nr_reg < 3) {
+ pr_err("min_nr_regions (%lu) must be at least 3\n",
+ min_nr_reg);
+ return -EINVAL;
+ }
+ if (min_nr_reg > max_nr_reg) {
+ pr_err("invalid nr_regions. min (%lu) > max (%lu)\n",
+ min_nr_reg, max_nr_reg);
return -EINVAL;
}
ctx->sample_interval = sample_int;
ctx->aggr_interval = aggr_int;
- ctx->nr_regions = nr_reg;
+ ctx->min_nr_regions = min_nr_reg;
+ ctx->max_nr_regions = max_nr_reg;
return 0;
}
--
2.17.1
From: SeongJae Park <[email protected]>
DAMON programming interface users are safe from pid recycling problem
since it uses 'struct pid *' as target id. However, debugfs interface
users might still get the problem since they should describe the target
ids with pid numbers.
This commit makes the debugfs interface to support pidfd target ids.
Using it, debugfs interface users can also easily be safe from the
races. That said, the pid numbers are stil supported for the simple
command line uses.
The pid numbers target ids usages are same to the old one. Therefore,
old users don't need to change anything. To use pidfd target ids, users
should add a prefix, 'pidfd ' in front of the numbers. Because pidfd is
process private, reading 'target_ids' file again will show pid numbers
of the target processes.
Signed-off-by: SeongJae Park <[email protected]>
---
mm/damon.c | 37 ++++++++++++++++++++++++++++++++++---
1 file changed, 34 insertions(+), 3 deletions(-)
diff --git a/mm/damon.c b/mm/damon.c
index 01003a1ff551..61d93f1ea974 100644
--- a/mm/damon.c
+++ b/mm/damon.c
@@ -1450,11 +1450,32 @@ static unsigned long *str_to_target_ids(const char *str, ssize_t len,
return ids;
}
+/* Returns pid for the given pidfd if it's valid, or NULL otherwise. */
+static struct pid *damon_get_pidfd_pid(unsigned int pidfd)
+{
+ struct fd f;
+ struct pid *pid;
+
+ f = fdget(pidfd);
+ if (!f.file)
+ return NULL;
+
+ pid = pidfd_pid(f.file);
+ if (!IS_ERR(pid))
+ get_pid(pid);
+ else
+ pid = NULL;
+
+ fdput(f);
+ return pid;
+}
+
static ssize_t debugfs_target_ids_write(struct file *file,
const char __user *buf, size_t count, loff_t *ppos)
{
struct damon_ctx *ctx = &damon_user_ctx;
- char *kbuf;
+ char *kbuf, *nrs;
+ bool received_pidfds = false;
unsigned long *targets;
ssize_t nr_targets;
ssize_t ret = count;
@@ -1466,13 +1487,23 @@ static ssize_t debugfs_target_ids_write(struct file *file,
if (IS_ERR(kbuf))
return PTR_ERR(kbuf);
- targets = str_to_target_ids(kbuf, ret, &nr_targets);
+ nrs = kbuf;
+ if (!strncmp(kbuf, "pidfd ", 6)) {
+ received_pidfds = true;
+ nrs = &kbuf[6];
+ }
+
+ targets = str_to_target_ids(nrs, ret, &nr_targets);
if (!targets) {
ret = -ENOMEM;
goto out;
}
- if (targetid_is_pid(ctx)) {
+ if (received_pidfds) {
+ for (i = 0; i < nr_targets; i++)
+ targets[i] = (unsigned long)damon_get_pidfd_pid(
+ (unsigned int)targets[i]);
+ } else if (targetid_is_pid(ctx)) {
for (i = 0; i < nr_targets; i++)
targets[i] = (unsigned long)find_get_pid(
(int)targets[i]);
--
2.17.1
From: SeongJae Park <[email protected]>
This commit adds a tracepoint for DAMON. It traces the monitoring
results of each region for each aggregation interval. Using this, DAMON
can easily integrated with tracepoints supporting tools such as perf.
Signed-off-by: SeongJae Park <[email protected]>
Reviewed-by: Leonard Foerster <[email protected]>
---
include/trace/events/damon.h | 43 ++++++++++++++++++++++++++++++++++++
mm/damon.c | 4 ++++
2 files changed, 47 insertions(+)
create mode 100644 include/trace/events/damon.h
diff --git a/include/trace/events/damon.h b/include/trace/events/damon.h
new file mode 100644
index 000000000000..2f422f4f1fb9
--- /dev/null
+++ b/include/trace/events/damon.h
@@ -0,0 +1,43 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM damon
+
+#if !defined(_TRACE_DAMON_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_DAMON_H
+
+#include <linux/damon.h>
+#include <linux/types.h>
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(damon_aggregated,
+
+ TP_PROTO(struct damon_target *t, struct damon_region *r,
+ unsigned int nr_regions),
+
+ TP_ARGS(t, r, nr_regions),
+
+ TP_STRUCT__entry(
+ __field(unsigned long, target_id)
+ __field(unsigned int, nr_regions)
+ __field(unsigned long, start)
+ __field(unsigned long, end)
+ __field(unsigned int, nr_accesses)
+ ),
+
+ TP_fast_assign(
+ __entry->target_id = t->id;
+ __entry->nr_regions = nr_regions;
+ __entry->start = r->ar.start;
+ __entry->end = r->ar.end;
+ __entry->nr_accesses = r->nr_accesses;
+ ),
+
+ TP_printk("target_id=%lu nr_regions=%u %lu-%lu: %u",
+ __entry->target_id, __entry->nr_regions,
+ __entry->start, __entry->end, __entry->nr_accesses)
+);
+
+#endif /* _TRACE_DAMON_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
diff --git a/mm/damon.c b/mm/damon.c
index b3420ba97fd2..65e65e779313 100644
--- a/mm/damon.c
+++ b/mm/damon.c
@@ -20,6 +20,8 @@
#define pr_fmt(fmt) "damon: " fmt
+#define CREATE_TRACE_POINTS
+
#include <linux/damon.h>
#include <linux/delay.h>
#include <linux/kthread.h>
@@ -31,6 +33,7 @@
#include <linux/sched/mm.h>
#include <linux/sched/task.h>
#include <linux/slab.h>
+#include <trace/events/damon.h>
/* Minimal region size. Every damon_region is aligned by this. */
#define MIN_REGION PAGE_SIZE
@@ -856,6 +859,7 @@ static void kdamond_reset_aggregated(struct damon_ctx *c)
damon_write_rbuf(c, &r->ar.end, sizeof(r->ar.end));
damon_write_rbuf(c, &r->nr_accesses,
sizeof(r->nr_accesses));
+ trace_damon_aggregated(t, r, nr);
r->nr_accesses = 0;
}
}
--
2.17.1
From: SeongJae Park <[email protected]>
This commit implements a debugfs interface for DAMON. It works for the
virtual address spaces monitoring.
DAMON exports four files, ``attrs``, ``target_ids``, ``record``, and
``monitor_on`` under its debugfs directory, ``<debugfs>/damon/``.
Attributes
----------
Users can read and write the ``sampling interval``, ``aggregation
interval``, ``regions update interval``, and min/max number of
monitoring target regions by reading from and writing to the ``attrs``
file. For example, below commands set those values to 5 ms, 100 ms,
1,000 ms, 10, 1000 and check it again::
# cd <debugfs>/damon
# echo 5000 100000 1000000 10 1000 > attrs
# cat attrs
5000 100000 1000000 10 1000
Target IDs
----------
Some types of address spaces supports multiple monitoring target. For
example, the virtual memory address spaces monitoring can have multiple
processes as the monitoring targets. Users can set the targets by
writing relevant id values of the targets to, and get the ids of the
current targets by reading from the ``target_ids`` file. In case of the
virtual address spaces monitoring, the values should be pids of the
monitoring target processes. For example, below commands set processes
having pids 42 and 4242 as the monitoring targets and check it again::
# cd <debugfs>/damon
# echo 42 4242 > target_ids
# cat target_ids
42 4242
Note that setting the target ids doesn't start the monitoring.
Record
------
DAMON supports direct monitoring result record feature. The recorded
results are first written to a buffer and flushed to a file in batch.
Users can set the size of the buffer and the path to the result file by
reading from and writing to the ``record`` file. For example, below
commands set the buffer to be 4 KiB and the result to be saved in
'/damon.data'.
# cd <debugfs>/damon
# echo 4096 /damon.data > record
# cat record
4096 /damon.data
Turning On/Off
--------------
Setting the files as described above doesn't incur effect unless you
explicitly start the monitoring. You can start, stop, and check the
current status of the monitoring by writing to and reading from the
``monitor_on`` file. Writing ``on`` to the file starts the monitoring
of the targets with the attributes. Writing ``off`` to the file stops
those. DAMON also stops if every targets are invalidated (in case of
the virtual memory monitoring, target processes are invalidated when
terminated). Below example commands turn on, off, and check the status
of DAMON::
# cd <debugfs>/damon
# echo on > monitor_on
# echo off > monitor_on
# cat monitor_on
off
Please note that you cannot write to the above-mentioned debugfs files
while the monitoring is turned on. If you write to the files while
DAMON is running, an error code such as ``-EBUSY`` will be returned.
Signed-off-by: SeongJae Park <[email protected]>
Reviewed-by: Leonard Foerster <[email protected]>
---
mm/damon.c | 396 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 395 insertions(+), 1 deletion(-)
diff --git a/mm/damon.c b/mm/damon.c
index 65e65e779313..01003a1ff551 100644
--- a/mm/damon.c
+++ b/mm/damon.c
@@ -15,6 +15,7 @@
* - Functions for the target validity check
* - Functions for DAMON core logics and features
* - Functions for the DAMON programming interface
+ * - Functions for the DAMON debugfs interface
* - Functions for the initialization
*/
@@ -23,6 +24,7 @@
#define CREATE_TRACE_POINTS
#include <linux/damon.h>
+#include <linux/debugfs.h>
#include <linux/delay.h>
#include <linux/kthread.h>
#include <linux/mm.h>
@@ -67,6 +69,21 @@
/* Get a random number in [l, r) */
#define damon_rand(l, r) (l + prandom_u32() % (r - l))
+/* A monitoring context for debugfs interface users. */
+static struct damon_ctx damon_user_ctx = {
+ .sample_interval = 5 * 1000,
+ .aggr_interval = 100 * 1000,
+ .regions_update_interval = 1000 * 1000,
+ .min_nr_regions = 10,
+ .max_nr_regions = 1000,
+
+ .init_target_regions = kdamond_init_vm_regions,
+ .update_target_regions = kdamond_update_vm_regions,
+ .prepare_access_checks = kdamond_prepare_vm_access_checks,
+ .check_accesses = kdamond_check_vm_accesses,
+ .target_valid = kdamond_vm_target_valid,
+};
+
/*
* Construct a damon_region struct
*
@@ -1289,13 +1306,390 @@ int damon_set_attrs(struct damon_ctx *ctx, unsigned long sample_int,
return 0;
}
+/*
+ * Functions for the DAMON debugfs interface
+ */
+
+static ssize_t debugfs_monitor_on_read(struct file *file,
+ char __user *buf, size_t count, loff_t *ppos)
+{
+ struct damon_ctx *ctx = &damon_user_ctx;
+ char monitor_on_buf[5];
+ bool monitor_on;
+ int len;
+
+ monitor_on = damon_kdamond_running(ctx);
+ len = snprintf(monitor_on_buf, 5, monitor_on ? "on\n" : "off\n");
+
+ return simple_read_from_buffer(buf, count, ppos, monitor_on_buf, len);
+}
+
+/*
+ * Returns non-empty string on success, negarive error code otherwise.
+ */
+static char *user_input_str(const char __user *buf, size_t count, loff_t *ppos)
+{
+ char *kbuf;
+ ssize_t ret;
+
+ /* We do not accept continuous write */
+ if (*ppos)
+ return ERR_PTR(-EINVAL);
+
+ kbuf = kmalloc(count + 1, GFP_KERNEL);
+ if (!kbuf)
+ return ERR_PTR(-ENOMEM);
+
+ ret = simple_write_to_buffer(kbuf, count + 1, ppos, buf, count);
+ if (ret != count) {
+ kfree(kbuf);
+ return ERR_PTR(-EIO);
+ }
+ kbuf[ret] = '\0';
+
+ return kbuf;
+}
+
+static ssize_t debugfs_monitor_on_write(struct file *file,
+ const char __user *buf, size_t count, loff_t *ppos)
+{
+ struct damon_ctx *ctx = &damon_user_ctx;
+ ssize_t ret = count;
+ char *kbuf;
+ int err;
+
+ kbuf = user_input_str(buf, count, ppos);
+ if (IS_ERR(kbuf))
+ return PTR_ERR(kbuf);
+
+ /* Remove white space */
+ if (sscanf(kbuf, "%s", kbuf) != 1)
+ return -EINVAL;
+ if (!strncmp(kbuf, "on", count))
+ err = damon_start(ctx);
+ else if (!strncmp(kbuf, "off", count))
+ err = damon_stop(ctx);
+ else
+ return -EINVAL;
+
+ if (err)
+ ret = err;
+ return ret;
+}
+
+#define targetid_is_pid(ctx) \
+ (ctx->target_valid == kdamond_vm_target_valid)
+
+static ssize_t sprint_target_ids(struct damon_ctx *ctx, char *buf, ssize_t len)
+{
+ struct damon_target *t;
+ unsigned long id;
+ int written = 0;
+ int rc;
+
+ damon_for_each_target(t, ctx) {
+ id = t->id;
+ if (targetid_is_pid(ctx))
+ /* Show pid numbers to debugfs users */
+ id = (unsigned long)pid_vnr((struct pid *)id);
+
+ rc = snprintf(&buf[written], len - written, "%lu ", id);
+ if (!rc)
+ return -ENOMEM;
+ written += rc;
+ }
+ if (written)
+ written -= 1;
+ written += snprintf(&buf[written], len - written, "\n");
+ return written;
+}
+
+static ssize_t debugfs_target_ids_read(struct file *file,
+ char __user *buf, size_t count, loff_t *ppos)
+{
+ struct damon_ctx *ctx = &damon_user_ctx;
+ ssize_t len;
+ char ids_buf[320];
+
+ mutex_lock(&ctx->kdamond_lock);
+ len = sprint_target_ids(ctx, ids_buf, 320);
+ mutex_unlock(&ctx->kdamond_lock);
+ if (len < 0)
+ return len;
+
+ return simple_read_from_buffer(buf, count, ppos, ids_buf, len);
+}
+
+/*
+ * Converts a string into an array of unsigned long integers
+ *
+ * Returns an array of unsigned long integers if the conversion success, or
+ * NULL otherwise.
+ */
+static unsigned long *str_to_target_ids(const char *str, ssize_t len,
+ ssize_t *nr_ids)
+{
+ unsigned long *ids;
+ const int max_nr_ids = 32;
+ unsigned long id;
+ int pos = 0, parsed, ret;
+
+ *nr_ids = 0;
+ ids = kmalloc_array(max_nr_ids, sizeof(id), GFP_KERNEL);
+ if (!ids)
+ return NULL;
+ while (*nr_ids < max_nr_ids && pos < len) {
+ ret = sscanf(&str[pos], "%lu%n", &id, &parsed);
+ pos += parsed;
+ if (ret != 1)
+ break;
+ ids[*nr_ids] = id;
+ *nr_ids += 1;
+ }
+
+ return ids;
+}
+
+static ssize_t debugfs_target_ids_write(struct file *file,
+ const char __user *buf, size_t count, loff_t *ppos)
+{
+ struct damon_ctx *ctx = &damon_user_ctx;
+ char *kbuf;
+ unsigned long *targets;
+ ssize_t nr_targets;
+ ssize_t ret = count;
+ struct damon_target *target;
+ int i;
+ int err;
+
+ kbuf = user_input_str(buf, count, ppos);
+ if (IS_ERR(kbuf))
+ return PTR_ERR(kbuf);
+
+ targets = str_to_target_ids(kbuf, ret, &nr_targets);
+ if (!targets) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ if (targetid_is_pid(ctx)) {
+ for (i = 0; i < nr_targets; i++)
+ targets[i] = (unsigned long)find_get_pid(
+ (int)targets[i]);
+ }
+
+ mutex_lock(&ctx->kdamond_lock);
+ if (ctx->kdamond) {
+ ret = -EINVAL;
+ goto unlock_out;
+ }
+
+ if (targetid_is_pid(ctx)) {
+ damon_for_each_target(target, ctx)
+ put_pid((struct pid *)target->id);
+ }
+
+ err = damon_set_targets(ctx, targets, nr_targets);
+ if (err)
+ ret = err;
+unlock_out:
+ mutex_unlock(&ctx->kdamond_lock);
+ kfree(targets);
+out:
+ kfree(kbuf);
+ return ret;
+}
+
+static ssize_t debugfs_record_read(struct file *file,
+ char __user *buf, size_t count, loff_t *ppos)
+{
+ struct damon_ctx *ctx = &damon_user_ctx;
+ char record_buf[20 + MAX_RFILE_PATH_LEN];
+ int ret;
+
+ mutex_lock(&ctx->kdamond_lock);
+ ret = snprintf(record_buf, ARRAY_SIZE(record_buf), "%u %s\n",
+ ctx->rbuf_len, ctx->rfile_path);
+ mutex_unlock(&ctx->kdamond_lock);
+ return simple_read_from_buffer(buf, count, ppos, record_buf, ret);
+}
+
+static ssize_t debugfs_record_write(struct file *file,
+ const char __user *buf, size_t count, loff_t *ppos)
+{
+ struct damon_ctx *ctx = &damon_user_ctx;
+ char *kbuf;
+ unsigned int rbuf_len;
+ char rfile_path[MAX_RFILE_PATH_LEN];
+ ssize_t ret = count;
+ int err;
+
+ kbuf = user_input_str(buf, count, ppos);
+ if (IS_ERR(kbuf))
+ return PTR_ERR(kbuf);
+
+ if (sscanf(kbuf, "%u %s",
+ &rbuf_len, rfile_path) != 2) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ mutex_lock(&ctx->kdamond_lock);
+ if (ctx->kdamond) {
+ ret = -EBUSY;
+ goto unlock_out;
+ }
+
+ err = damon_set_recording(ctx, rbuf_len, rfile_path);
+ if (err)
+ ret = err;
+unlock_out:
+ mutex_unlock(&ctx->kdamond_lock);
+out:
+ kfree(kbuf);
+ return ret;
+}
+
+static ssize_t debugfs_attrs_read(struct file *file,
+ char __user *buf, size_t count, loff_t *ppos)
+{
+ struct damon_ctx *ctx = &damon_user_ctx;
+ char kbuf[128];
+ int ret;
+
+ mutex_lock(&ctx->kdamond_lock);
+ ret = snprintf(kbuf, ARRAY_SIZE(kbuf), "%lu %lu %lu %lu %lu\n",
+ ctx->sample_interval, ctx->aggr_interval,
+ ctx->regions_update_interval, ctx->min_nr_regions,
+ ctx->max_nr_regions);
+ mutex_unlock(&ctx->kdamond_lock);
+
+ return simple_read_from_buffer(buf, count, ppos, kbuf, ret);
+}
+
+static ssize_t debugfs_attrs_write(struct file *file,
+ const char __user *buf, size_t count, loff_t *ppos)
+{
+ struct damon_ctx *ctx = &damon_user_ctx;
+ unsigned long s, a, r, minr, maxr;
+ char *kbuf;
+ ssize_t ret = count;
+ int err;
+
+ kbuf = user_input_str(buf, count, ppos);
+ if (IS_ERR(kbuf))
+ return PTR_ERR(kbuf);
+
+ if (sscanf(kbuf, "%lu %lu %lu %lu %lu",
+ &s, &a, &r, &minr, &maxr) != 5) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ mutex_lock(&ctx->kdamond_lock);
+ if (ctx->kdamond) {
+ ret = -EBUSY;
+ goto unlock_out;
+ }
+
+ err = damon_set_attrs(ctx, s, a, r, minr, maxr);
+ if (err)
+ ret = err;
+unlock_out:
+ mutex_unlock(&ctx->kdamond_lock);
+out:
+ kfree(kbuf);
+ return ret;
+}
+
+static const struct file_operations monitor_on_fops = {
+ .owner = THIS_MODULE,
+ .read = debugfs_monitor_on_read,
+ .write = debugfs_monitor_on_write,
+};
+
+static const struct file_operations target_ids_fops = {
+ .owner = THIS_MODULE,
+ .read = debugfs_target_ids_read,
+ .write = debugfs_target_ids_write,
+};
+
+static const struct file_operations record_fops = {
+ .owner = THIS_MODULE,
+ .read = debugfs_record_read,
+ .write = debugfs_record_write,
+};
+
+static const struct file_operations attrs_fops = {
+ .owner = THIS_MODULE,
+ .read = debugfs_attrs_read,
+ .write = debugfs_attrs_write,
+};
+
+static struct dentry *debugfs_root;
+
+static int __init damon_debugfs_init(void)
+{
+ const char * const file_names[] = {"attrs", "record",
+ "target_ids", "monitor_on"};
+ const struct file_operations *fops[] = {&attrs_fops, &record_fops,
+ &target_ids_fops, &monitor_on_fops};
+ int i;
+
+ debugfs_root = debugfs_create_dir("damon", NULL);
+ if (!debugfs_root) {
+ pr_err("failed to create the debugfs dir\n");
+ return -ENOMEM;
+ }
+
+ for (i = 0; i < ARRAY_SIZE(file_names); i++) {
+ if (!debugfs_create_file(file_names[i], 0600, debugfs_root,
+ NULL, fops[i])) {
+ pr_err("failed to create %s file\n", file_names[i]);
+ return -ENOMEM;
+ }
+ }
+
+ return 0;
+}
+
+static int __init damon_init_user_ctx(void)
+{
+ int rc;
+
+ struct damon_ctx *ctx = &damon_user_ctx;
+
+ ktime_get_coarse_ts64(&ctx->last_aggregation);
+ ctx->last_regions_update = ctx->last_aggregation;
+
+ rc = damon_set_recording(ctx, 1024 * 1024, "/damon.data");
+ if (rc)
+ return rc;
+
+ mutex_init(&ctx->kdamond_lock);
+
+ INIT_LIST_HEAD(&ctx->targets_list);
+
+ return 0;
+}
+
/*
* Functions for the initialization
*/
static int __init damon_init(void)
{
- return 0;
+ int rc;
+
+ rc = damon_init_user_ctx();
+ if (rc)
+ return rc;
+
+ rc = damon_debugfs_init();
+ if (rc)
+ pr_err("%s: debugfs init failed\n", __func__);
+
+ return rc;
}
module_init(damon_init);
--
2.17.1
From: SeongJae Park <[email protected]>
This commit adds kunit based unit tests for DAMON.
Signed-off-by: SeongJae Park <[email protected]>
Reviewed-by: Brendan Higgins <[email protected]>
---
mm/Kconfig | 11 +
mm/damon-test.h | 671 ++++++++++++++++++++++++++++++++++++++++++++++++
mm/damon.c | 6 +
3 files changed, 688 insertions(+)
create mode 100644 mm/damon-test.h
diff --git a/mm/Kconfig b/mm/Kconfig
index 21cbd394bc78..d7be006813f2 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -894,4 +894,15 @@ config DAMON
more information.
If unsure, say N.
+config DAMON_KUNIT_TEST
+ bool "Test for damon"
+ depends on DAMON=y && KUNIT
+ help
+ This builds the DAMON Kunit test suite.
+
+ For more information on KUnit and unit tests in general, please refer
+ to the KUnit documentation.
+
+ If unsure, say N.
+
endmenu
diff --git a/mm/damon-test.h b/mm/damon-test.h
new file mode 100644
index 000000000000..71413ffc1dcb
--- /dev/null
+++ b/mm/damon-test.h
@@ -0,0 +1,671 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Data Access Monitor Unit Tests
+ *
+ * Copyright 2019 Amazon.com, Inc. or its affiliates. All rights reserved.
+ *
+ * Author: SeongJae Park <[email protected]>
+ */
+
+#ifdef CONFIG_DAMON_KUNIT_TEST
+
+#ifndef _DAMON_TEST_H
+#define _DAMON_TEST_H
+
+#include <kunit/test.h>
+
+static void damon_test_str_to_target_ids(struct kunit *test)
+{
+ char *question;
+ unsigned long *answers;
+ unsigned long expected[] = {12, 35, 46};
+ ssize_t nr_integers = 0, i;
+
+ question = "123";
+ answers = str_to_target_ids(question, strnlen(question, 128),
+ &nr_integers);
+ KUNIT_EXPECT_EQ(test, (ssize_t)1, nr_integers);
+ KUNIT_EXPECT_EQ(test, 123ul, answers[0]);
+ kfree(answers);
+
+ question = "123abc";
+ answers = str_to_target_ids(question, strnlen(question, 128),
+ &nr_integers);
+ KUNIT_EXPECT_EQ(test, (ssize_t)1, nr_integers);
+ KUNIT_EXPECT_EQ(test, 123ul, answers[0]);
+ kfree(answers);
+
+ question = "a123";
+ answers = str_to_target_ids(question, strnlen(question, 128),
+ &nr_integers);
+ KUNIT_EXPECT_EQ(test, (ssize_t)0, nr_integers);
+ kfree(answers);
+
+ question = "12 35";
+ answers = str_to_target_ids(question, strnlen(question, 128),
+ &nr_integers);
+ KUNIT_EXPECT_EQ(test, (ssize_t)2, nr_integers);
+ for (i = 0; i < nr_integers; i++)
+ KUNIT_EXPECT_EQ(test, expected[i], answers[i]);
+ kfree(answers);
+
+ question = "12 35 46";
+ answers = str_to_target_ids(question, strnlen(question, 128),
+ &nr_integers);
+ KUNIT_EXPECT_EQ(test, (ssize_t)3, nr_integers);
+ for (i = 0; i < nr_integers; i++)
+ KUNIT_EXPECT_EQ(test, expected[i], answers[i]);
+ kfree(answers);
+
+ question = "12 35 abc 46";
+ answers = str_to_target_ids(question, strnlen(question, 128),
+ &nr_integers);
+ KUNIT_EXPECT_EQ(test, (ssize_t)2, nr_integers);
+ for (i = 0; i < 2; i++)
+ KUNIT_EXPECT_EQ(test, expected[i], answers[i]);
+ kfree(answers);
+
+ question = "";
+ answers = str_to_target_ids(question, strnlen(question, 128),
+ &nr_integers);
+ KUNIT_EXPECT_EQ(test, (ssize_t)0, nr_integers);
+ kfree(answers);
+
+ question = "\n";
+ answers = str_to_target_ids(question, strnlen(question, 128),
+ &nr_integers);
+ KUNIT_EXPECT_EQ(test, (ssize_t)0, nr_integers);
+ kfree(answers);
+}
+
+static void damon_test_regions(struct kunit *test)
+{
+ struct damon_region *r;
+ struct damon_target *t;
+
+ r = damon_new_region(1, 2);
+ KUNIT_EXPECT_EQ(test, 1ul, r->ar.start);
+ KUNIT_EXPECT_EQ(test, 2ul, r->ar.end);
+ KUNIT_EXPECT_EQ(test, 0u, r->nr_accesses);
+
+ t = damon_new_target(42);
+ KUNIT_EXPECT_EQ(test, 0u, nr_damon_regions(t));
+
+ damon_add_region(r, t);
+ KUNIT_EXPECT_EQ(test, 1u, nr_damon_regions(t));
+
+ damon_del_region(r);
+ KUNIT_EXPECT_EQ(test, 0u, nr_damon_regions(t));
+
+ damon_free_target(t);
+}
+
+static void damon_test_target(struct kunit *test)
+{
+ struct damon_ctx *c = &damon_user_ctx;
+ struct damon_target *t;
+
+ t = damon_new_target(42);
+ KUNIT_EXPECT_EQ(test, 42ul, t->id);
+ KUNIT_EXPECT_EQ(test, 0u, nr_damon_targets(c));
+
+ damon_add_target(&damon_user_ctx, t);
+ KUNIT_EXPECT_EQ(test, 1u, nr_damon_targets(c));
+
+ damon_destroy_target(t);
+ KUNIT_EXPECT_EQ(test, 0u, nr_damon_targets(c));
+}
+
+static void damon_test_set_targets(struct kunit *test)
+{
+ struct damon_ctx *ctx = &damon_user_ctx;
+ unsigned long ids[] = {1, 2, 3};
+ char buf[64];
+
+ /* Make DAMON consider target id as plain number */
+ ctx->target_valid = NULL;
+
+ damon_set_targets(ctx, ids, 3);
+ sprint_target_ids(ctx, buf, 64);
+ KUNIT_EXPECT_STREQ(test, (char *)buf, "1 2 3\n");
+
+ damon_set_targets(ctx, NULL, 0);
+ sprint_target_ids(ctx, buf, 64);
+ KUNIT_EXPECT_STREQ(test, (char *)buf, "\n");
+
+ damon_set_targets(ctx, (unsigned long []){1, 2}, 2);
+ sprint_target_ids(ctx, buf, 64);
+ KUNIT_EXPECT_STREQ(test, (char *)buf, "1 2\n");
+
+ damon_set_targets(ctx, (unsigned long []){2}, 1);
+ sprint_target_ids(ctx, buf, 64);
+ KUNIT_EXPECT_STREQ(test, (char *)buf, "2\n");
+
+ damon_set_targets(ctx, NULL, 0);
+ sprint_target_ids(ctx, buf, 64);
+ KUNIT_EXPECT_STREQ(test, (char *)buf, "\n");
+}
+
+static void damon_test_set_recording(struct kunit *test)
+{
+ struct damon_ctx *ctx = &damon_user_ctx;
+ int err;
+
+ err = damon_set_recording(ctx, 42, "foo");
+ KUNIT_EXPECT_EQ(test, err, -EINVAL);
+ damon_set_recording(ctx, 4242, "foo.bar");
+ KUNIT_EXPECT_EQ(test, ctx->rbuf_len, 4242u);
+ KUNIT_EXPECT_STREQ(test, ctx->rfile_path, "foo.bar");
+ damon_set_recording(ctx, 424242, "foo");
+ KUNIT_EXPECT_EQ(test, ctx->rbuf_len, 424242u);
+ KUNIT_EXPECT_STREQ(test, ctx->rfile_path, "foo");
+}
+
+static void __link_vmas(struct vm_area_struct *vmas, ssize_t nr_vmas)
+{
+ int i, j;
+ unsigned long largest_gap, gap;
+
+ if (!nr_vmas)
+ return;
+
+ for (i = 0; i < nr_vmas - 1; i++) {
+ vmas[i].vm_next = &vmas[i + 1];
+
+ vmas[i].vm_rb.rb_left = NULL;
+ vmas[i].vm_rb.rb_right = &vmas[i + 1].vm_rb;
+
+ largest_gap = 0;
+ for (j = i; j < nr_vmas; j++) {
+ if (j == 0)
+ continue;
+ gap = vmas[j].vm_start - vmas[j - 1].vm_end;
+ if (gap > largest_gap)
+ largest_gap = gap;
+ }
+ vmas[i].rb_subtree_gap = largest_gap;
+ }
+ vmas[i].vm_next = NULL;
+ vmas[i].vm_rb.rb_right = NULL;
+ vmas[i].rb_subtree_gap = 0;
+}
+
+/*
+ * Test damon_three_regions_in_vmas() function
+ *
+ * In case of virtual memory address spaces monitoring, DAMON converts the
+ * complex and dynamic memory mappings of each target task to three
+ * discontiguous regions which cover every mapped areas. However, the three
+ * regions should not include the two biggest unmapped areas in the original
+ * mapping, because the two biggest areas are normally the areas between 1)
+ * heap and the mmap()-ed regions, and 2) the mmap()-ed regions and stack.
+ * Because these two unmapped areas are very huge but obviously never accessed,
+ * covering the region is just a waste.
+ *
+ * 'damon_three_regions_in_vmas() receives an address space of a process. It
+ * first identifies the start of mappings, end of mappings, and the two biggest
+ * unmapped areas. After that, based on the information, it constructs the
+ * three regions and returns. For more detail, refer to the comment of
+ * 'damon_init_regions_of()' function definition in 'mm/damon.c' file.
+ *
+ * For example, suppose virtual address ranges of 10-20, 20-25, 200-210,
+ * 210-220, 300-305, and 307-330 (Other comments represent this mappings in
+ * more short form: 10-20-25, 200-210-220, 300-305, 307-330) of a process are
+ * mapped. To cover every mappings, the three regions should start with 10,
+ * and end with 305. The process also has three unmapped areas, 25-200,
+ * 220-300, and 305-307. Among those, 25-200 and 220-300 are the biggest two
+ * unmapped areas, and thus it should be converted to three regions of 10-25,
+ * 200-220, and 300-330.
+ */
+static void damon_test_three_regions_in_vmas(struct kunit *test)
+{
+ struct damon_addr_range regions[3] = {0,};
+ /* 10-20-25, 200-210-220, 300-305, 307-330 */
+ struct vm_area_struct vmas[] = {
+ (struct vm_area_struct) {.vm_start = 10, .vm_end = 20},
+ (struct vm_area_struct) {.vm_start = 20, .vm_end = 25},
+ (struct vm_area_struct) {.vm_start = 200, .vm_end = 210},
+ (struct vm_area_struct) {.vm_start = 210, .vm_end = 220},
+ (struct vm_area_struct) {.vm_start = 300, .vm_end = 305},
+ (struct vm_area_struct) {.vm_start = 307, .vm_end = 330},
+ };
+
+ __link_vmas(vmas, 6);
+
+ damon_three_regions_in_vmas(&vmas[0], regions);
+
+ KUNIT_EXPECT_EQ(test, 10ul, regions[0].start);
+ KUNIT_EXPECT_EQ(test, 25ul, regions[0].end);
+ KUNIT_EXPECT_EQ(test, 200ul, regions[1].start);
+ KUNIT_EXPECT_EQ(test, 220ul, regions[1].end);
+ KUNIT_EXPECT_EQ(test, 300ul, regions[2].start);
+ KUNIT_EXPECT_EQ(test, 330ul, regions[2].end);
+}
+
+/* Clean up global state of damon */
+static void damon_cleanup_global_state(void)
+{
+ struct damon_target *t, *next;
+
+ damon_for_each_target_safe(t, next, &damon_user_ctx)
+ damon_destroy_target(t);
+
+ damon_user_ctx.rbuf_offset = 0;
+}
+
+/*
+ * Test kdamond_reset_aggregated()
+ *
+ * DAMON checks access to each region and aggregates this information as the
+ * access frequency of each region. In detail, it increases '->nr_accesses' of
+ * regions that an access has confirmed. 'kdamond_reset_aggregated()' flushes
+ * the aggregated information ('->nr_accesses' of each regions) to the result
+ * buffer. As a result of the flushing, the '->nr_accesses' of regions are
+ * initialized to zero.
+ */
+static void damon_test_aggregate(struct kunit *test)
+{
+ struct damon_ctx *ctx = &damon_user_ctx;
+ unsigned long target_ids[] = {1, 2, 3};
+ unsigned long saddr[][3] = {{10, 20, 30}, {5, 42, 49}, {13, 33, 55} };
+ unsigned long eaddr[][3] = {{15, 27, 40}, {31, 45, 55}, {23, 44, 66} };
+ unsigned long accesses[][3] = {{42, 95, 84}, {10, 20, 30}, {0, 1, 2} };
+ struct damon_target *t;
+ struct damon_region *r;
+ int it, ir;
+ ssize_t sz, sr, sp;
+
+ damon_set_recording(ctx, 4242, "damon.data");
+ damon_set_targets(ctx, target_ids, 3);
+
+ it = 0;
+ damon_for_each_target(t, ctx) {
+ for (ir = 0; ir < 3; ir++) {
+ r = damon_new_region(saddr[it][ir], eaddr[it][ir]);
+ r->nr_accesses = accesses[it][ir];
+ damon_add_region(r, t);
+ }
+ it++;
+ }
+ kdamond_reset_aggregated(ctx);
+ it = 0;
+ damon_for_each_target(t, ctx) {
+ ir = 0;
+ /* '->nr_accesses' should be zeroed */
+ damon_for_each_region(r, t) {
+ KUNIT_EXPECT_EQ(test, 0u, r->nr_accesses);
+ ir++;
+ }
+ /* regions should be preserved */
+ KUNIT_EXPECT_EQ(test, 3, ir);
+ it++;
+ }
+ /* targets also should be preserved */
+ KUNIT_EXPECT_EQ(test, 3, it);
+
+ /* The aggregated information should be written in the buffer */
+ sr = sizeof(r->ar.start) + sizeof(r->ar.end) + sizeof(r->nr_accesses);
+ sp = sizeof(t->id) + sizeof(unsigned int) + 3 * sr;
+ sz = sizeof(struct timespec64) + sizeof(unsigned int) + 3 * sp;
+ KUNIT_EXPECT_EQ(test, (unsigned int)sz, ctx->rbuf_offset);
+
+ damon_set_recording(ctx, 0, "damon.data");
+ damon_cleanup_global_state();
+}
+
+static void damon_test_write_rbuf(struct kunit *test)
+{
+ struct damon_ctx *ctx = &damon_user_ctx;
+ char *data;
+
+ damon_set_recording(&damon_user_ctx, 4242, "damon.data");
+
+ data = "hello";
+ damon_write_rbuf(ctx, data, strnlen(data, 256));
+ KUNIT_EXPECT_EQ(test, ctx->rbuf_offset, 5u);
+
+ damon_write_rbuf(ctx, data, 0);
+ KUNIT_EXPECT_EQ(test, ctx->rbuf_offset, 5u);
+
+ KUNIT_EXPECT_STREQ(test, (char *)ctx->rbuf, data);
+ damon_set_recording(&damon_user_ctx, 0, "damon.data");
+}
+
+static struct damon_region *__nth_region_of(struct damon_target *t, int idx)
+{
+ struct damon_region *r;
+ unsigned int i = 0;
+
+ damon_for_each_region(r, t) {
+ if (i++ == idx)
+ return r;
+ }
+
+ return NULL;
+}
+
+/*
+ * Test 'damon_apply_three_regions()'
+ *
+ * test kunit object
+ * regions an array containing start/end addresses of current
+ * monitoring target regions
+ * nr_regions the number of the addresses in 'regions'
+ * three_regions The three regions that need to be applied now
+ * expected start/end addresses of monitoring target regions that
+ * 'three_regions' are applied
+ * nr_expected the number of addresses in 'expected'
+ *
+ * The memory mapping of the target processes changes dynamically. To follow
+ * the change, DAMON periodically reads the mappings, simplifies it to the
+ * three regions, and updates the monitoring target regions to fit in the three
+ * regions. The update of current target regions is the role of
+ * 'damon_apply_three_regions()'.
+ *
+ * This test passes the given target regions and the new three regions that
+ * need to be applied to the function and check whether it updates the regions
+ * as expected.
+ */
+static void damon_do_test_apply_three_regions(struct kunit *test,
+ unsigned long *regions, int nr_regions,
+ struct damon_addr_range *three_regions,
+ unsigned long *expected, int nr_expected)
+{
+ struct damon_target *t;
+ struct damon_region *r;
+ int i;
+
+ t = damon_new_target(42);
+ for (i = 0; i < nr_regions / 2; i++) {
+ r = damon_new_region(regions[i * 2], regions[i * 2 + 1]);
+ damon_add_region(r, t);
+ }
+ damon_add_target(&damon_user_ctx, t);
+
+ damon_apply_three_regions(&damon_user_ctx, t, three_regions);
+
+ for (i = 0; i < nr_expected / 2; i++) {
+ r = __nth_region_of(t, i);
+ KUNIT_EXPECT_EQ(test, r->ar.start, expected[i * 2]);
+ KUNIT_EXPECT_EQ(test, r->ar.end, expected[i * 2 + 1]);
+ }
+
+ damon_cleanup_global_state();
+}
+
+/*
+ * This function test most common case where the three big regions are only
+ * slightly changed. Target regions should adjust their boundary (10-20-30,
+ * 50-55, 70-80, 90-100) to fit with the new big regions or remove target
+ * regions (57-79) that now out of the three regions.
+ */
+static void damon_test_apply_three_regions1(struct kunit *test)
+{
+ /* 10-20-30, 50-55-57-59, 70-80-90-100 */
+ unsigned long regions[] = {10, 20, 20, 30, 50, 55, 55, 57, 57, 59,
+ 70, 80, 80, 90, 90, 100};
+ /* 5-27, 45-55, 73-104 */
+ struct damon_addr_range new_three_regions[3] = {
+ (struct damon_addr_range){.start = 5, .end = 27},
+ (struct damon_addr_range){.start = 45, .end = 55},
+ (struct damon_addr_range){.start = 73, .end = 104} };
+ /* 5-20-27, 45-55, 73-80-90-104 */
+ unsigned long expected[] = {5, 20, 20, 27, 45, 55,
+ 73, 80, 80, 90, 90, 104};
+
+ damon_do_test_apply_three_regions(test, regions, ARRAY_SIZE(regions),
+ new_three_regions, expected, ARRAY_SIZE(expected));
+}
+
+/*
+ * Test slightly bigger change. Similar to above, but the second big region
+ * now require two target regions (50-55, 57-59) to be removed.
+ */
+static void damon_test_apply_three_regions2(struct kunit *test)
+{
+ /* 10-20-30, 50-55-57-59, 70-80-90-100 */
+ unsigned long regions[] = {10, 20, 20, 30, 50, 55, 55, 57, 57, 59,
+ 70, 80, 80, 90, 90, 100};
+ /* 5-27, 56-57, 65-104 */
+ struct damon_addr_range new_three_regions[3] = {
+ (struct damon_addr_range){.start = 5, .end = 27},
+ (struct damon_addr_range){.start = 56, .end = 57},
+ (struct damon_addr_range){.start = 65, .end = 104} };
+ /* 5-20-27, 56-57, 65-80-90-104 */
+ unsigned long expected[] = {5, 20, 20, 27, 56, 57,
+ 65, 80, 80, 90, 90, 104};
+
+ damon_do_test_apply_three_regions(test, regions, ARRAY_SIZE(regions),
+ new_three_regions, expected, ARRAY_SIZE(expected));
+}
+
+/*
+ * Test a big change. The second big region has totally freed and mapped to
+ * different area (50-59 -> 61-63). The target regions which were in the old
+ * second big region (50-55-57-59) should be removed and new target region
+ * covering the second big region (61-63) should be created.
+ */
+static void damon_test_apply_three_regions3(struct kunit *test)
+{
+ /* 10-20-30, 50-55-57-59, 70-80-90-100 */
+ unsigned long regions[] = {10, 20, 20, 30, 50, 55, 55, 57, 57, 59,
+ 70, 80, 80, 90, 90, 100};
+ /* 5-27, 61-63, 65-104 */
+ struct damon_addr_range new_three_regions[3] = {
+ (struct damon_addr_range){.start = 5, .end = 27},
+ (struct damon_addr_range){.start = 61, .end = 63},
+ (struct damon_addr_range){.start = 65, .end = 104} };
+ /* 5-20-27, 61-63, 65-80-90-104 */
+ unsigned long expected[] = {5, 20, 20, 27, 61, 63,
+ 65, 80, 80, 90, 90, 104};
+
+ damon_do_test_apply_three_regions(test, regions, ARRAY_SIZE(regions),
+ new_three_regions, expected, ARRAY_SIZE(expected));
+}
+
+/*
+ * Test another big change. Both of the second and third big regions (50-59
+ * and 70-100) has totally freed and mapped to different area (30-32 and
+ * 65-68). The target regions which were in the old second and third big
+ * regions should now be removed and new target regions covering the new second
+ * and third big regions should be crated.
+ */
+static void damon_test_apply_three_regions4(struct kunit *test)
+{
+ /* 10-20-30, 50-55-57-59, 70-80-90-100 */
+ unsigned long regions[] = {10, 20, 20, 30, 50, 55, 55, 57, 57, 59,
+ 70, 80, 80, 90, 90, 100};
+ /* 5-7, 30-32, 65-68 */
+ struct damon_addr_range new_three_regions[3] = {
+ (struct damon_addr_range){.start = 5, .end = 7},
+ (struct damon_addr_range){.start = 30, .end = 32},
+ (struct damon_addr_range){.start = 65, .end = 68} };
+ /* expect 5-7, 30-32, 65-68 */
+ unsigned long expected[] = {5, 7, 30, 32, 65, 68};
+
+ damon_do_test_apply_three_regions(test, regions, ARRAY_SIZE(regions),
+ new_three_regions, expected, ARRAY_SIZE(expected));
+}
+
+static void damon_test_split_evenly(struct kunit *test)
+{
+ struct damon_ctx *c = &damon_user_ctx;
+ struct damon_target *t;
+ struct damon_region *r;
+ unsigned long i;
+
+ KUNIT_EXPECT_EQ(test, damon_split_region_evenly(c, NULL, 5), -EINVAL);
+
+ t = damon_new_target(42);
+ r = damon_new_region(0, 100);
+ KUNIT_EXPECT_EQ(test, damon_split_region_evenly(c, r, 0), -EINVAL);
+
+ damon_add_region(r, t);
+ KUNIT_EXPECT_EQ(test, damon_split_region_evenly(c, r, 10), 0);
+ KUNIT_EXPECT_EQ(test, nr_damon_regions(t), 10u);
+
+ i = 0;
+ damon_for_each_region(r, t) {
+ KUNIT_EXPECT_EQ(test, r->ar.start, i++ * 10);
+ KUNIT_EXPECT_EQ(test, r->ar.end, i * 10);
+ }
+ damon_free_target(t);
+
+ t = damon_new_target(42);
+ r = damon_new_region(5, 59);
+ damon_add_region(r, t);
+ KUNIT_EXPECT_EQ(test, damon_split_region_evenly(c, r, 5), 0);
+ KUNIT_EXPECT_EQ(test, nr_damon_regions(t), 5u);
+
+ i = 0;
+ damon_for_each_region(r, t) {
+ if (i == 4)
+ break;
+ KUNIT_EXPECT_EQ(test, r->ar.start, 5 + 10 * i++);
+ KUNIT_EXPECT_EQ(test, r->ar.end, 5 + 10 * i);
+ }
+ KUNIT_EXPECT_EQ(test, r->ar.start, 5 + 10 * i);
+ KUNIT_EXPECT_EQ(test, r->ar.end, 59ul);
+ damon_free_target(t);
+
+ t = damon_new_target(42);
+ r = damon_new_region(5, 6);
+ damon_add_region(r, t);
+ KUNIT_EXPECT_EQ(test, damon_split_region_evenly(c, r, 2), -EINVAL);
+ KUNIT_EXPECT_EQ(test, nr_damon_regions(t), 1u);
+
+ damon_for_each_region(r, t) {
+ KUNIT_EXPECT_EQ(test, r->ar.start, 5ul);
+ KUNIT_EXPECT_EQ(test, r->ar.end, 6ul);
+ }
+ damon_free_target(t);
+}
+
+static void damon_test_split_at(struct kunit *test)
+{
+ struct damon_target *t;
+ struct damon_region *r;
+
+ t = damon_new_target(42);
+ r = damon_new_region(0, 100);
+ damon_add_region(r, t);
+ damon_split_region_at(&damon_user_ctx, r, 25);
+ KUNIT_EXPECT_EQ(test, r->ar.start, 0ul);
+ KUNIT_EXPECT_EQ(test, r->ar.end, 25ul);
+
+ r = damon_next_region(r);
+ KUNIT_EXPECT_EQ(test, r->ar.start, 25ul);
+ KUNIT_EXPECT_EQ(test, r->ar.end, 100ul);
+
+ damon_free_target(t);
+}
+
+static void damon_test_merge_two(struct kunit *test)
+{
+ struct damon_target *t;
+ struct damon_region *r, *r2, *r3;
+ int i;
+
+ t = damon_new_target(42);
+ r = damon_new_region(0, 100);
+ r->nr_accesses = 10;
+ damon_add_region(r, t);
+ r2 = damon_new_region(100, 300);
+ r2->nr_accesses = 20;
+ damon_add_region(r2, t);
+
+ damon_merge_two_regions(r, r2);
+ KUNIT_EXPECT_EQ(test, r->ar.start, 0ul);
+ KUNIT_EXPECT_EQ(test, r->ar.end, 300ul);
+ KUNIT_EXPECT_EQ(test, r->nr_accesses, 16u);
+
+ i = 0;
+ damon_for_each_region(r3, t) {
+ KUNIT_EXPECT_PTR_EQ(test, r, r3);
+ i++;
+ }
+ KUNIT_EXPECT_EQ(test, i, 1);
+
+ damon_free_target(t);
+}
+
+static void damon_test_merge_regions_of(struct kunit *test)
+{
+ struct damon_target *t;
+ struct damon_region *r;
+ unsigned long sa[] = {0, 100, 114, 122, 130, 156, 170, 184};
+ unsigned long ea[] = {100, 112, 122, 130, 156, 170, 184, 230};
+ unsigned int nrs[] = {0, 0, 10, 10, 20, 30, 1, 2};
+
+ unsigned long saddrs[] = {0, 114, 130, 156, 170};
+ unsigned long eaddrs[] = {112, 130, 156, 170, 230};
+ int i;
+
+ t = damon_new_target(42);
+ for (i = 0; i < ARRAY_SIZE(sa); i++) {
+ r = damon_new_region(sa[i], ea[i]);
+ r->nr_accesses = nrs[i];
+ damon_add_region(r, t);
+ }
+
+ damon_merge_regions_of(t, 9, 9999);
+ /* 0-112, 114-130, 130-156, 156-170 */
+ KUNIT_EXPECT_EQ(test, nr_damon_regions(t), 5u);
+ for (i = 0; i < 5; i++) {
+ r = __nth_region_of(t, i);
+ KUNIT_EXPECT_EQ(test, r->ar.start, saddrs[i]);
+ KUNIT_EXPECT_EQ(test, r->ar.end, eaddrs[i]);
+ }
+ damon_free_target(t);
+}
+
+static void damon_test_split_regions_of(struct kunit *test)
+{
+ struct damon_target *t;
+ struct damon_region *r;
+
+ t = damon_new_target(42);
+ r = damon_new_region(0, 22);
+ damon_add_region(r, t);
+ damon_split_regions_of(&damon_user_ctx, t, 2);
+ KUNIT_EXPECT_EQ(test, nr_damon_regions(t), 2u);
+ damon_free_target(t);
+
+ t = damon_new_target(42);
+ r = damon_new_region(0, 220);
+ damon_add_region(r, t);
+ damon_split_regions_of(&damon_user_ctx, t, 4);
+ KUNIT_EXPECT_EQ(test, nr_damon_regions(t), 4u);
+ damon_free_target(t);
+}
+
+static struct kunit_case damon_test_cases[] = {
+ KUNIT_CASE(damon_test_str_to_target_ids),
+ KUNIT_CASE(damon_test_target),
+ KUNIT_CASE(damon_test_regions),
+ KUNIT_CASE(damon_test_set_targets),
+ KUNIT_CASE(damon_test_set_recording),
+ KUNIT_CASE(damon_test_three_regions_in_vmas),
+ KUNIT_CASE(damon_test_aggregate),
+ KUNIT_CASE(damon_test_write_rbuf),
+ KUNIT_CASE(damon_test_apply_three_regions1),
+ KUNIT_CASE(damon_test_apply_three_regions2),
+ KUNIT_CASE(damon_test_apply_three_regions3),
+ KUNIT_CASE(damon_test_apply_three_regions4),
+ KUNIT_CASE(damon_test_split_evenly),
+ KUNIT_CASE(damon_test_split_at),
+ KUNIT_CASE(damon_test_merge_two),
+ KUNIT_CASE(damon_test_merge_regions_of),
+ KUNIT_CASE(damon_test_split_regions_of),
+ {},
+};
+
+static struct kunit_suite damon_test_suite = {
+ .name = "damon",
+ .test_cases = damon_test_cases,
+};
+kunit_test_suite(damon_test_suite);
+
+#endif /* _DAMON_TEST_H */
+
+#endif /* CONFIG_DAMON_KUNIT_TEST */
diff --git a/mm/damon.c b/mm/damon.c
index 61d93f1ea974..114ef319eeab 100644
--- a/mm/damon.c
+++ b/mm/damon.c
@@ -38,7 +38,11 @@
#include <trace/events/damon.h>
/* Minimal region size. Every damon_region is aligned by this. */
+#ifndef CONFIG_DAMON_KUNIT_TEST
#define MIN_REGION PAGE_SIZE
+#else
+#define MIN_REGION 1
+#endif
/*
* Functions and macros for DAMON data structures
@@ -1724,3 +1728,5 @@ static int __init damon_init(void)
}
module_init(damon_init);
+
+#include "damon-test.h"
--
2.17.1
From: SeongJae Park <[email protected]>
This commit adds documents for DAMON under
`Documentation/admin-guide/mm/damon/` and `Documentation/vm/damon/`.
Signed-off-by: SeongJae Park <[email protected]>
---
Documentation/admin-guide/mm/damon/guide.rst | 157 ++++++++++
Documentation/admin-guide/mm/damon/index.rst | 15 +
Documentation/admin-guide/mm/damon/plans.rst | 29 ++
Documentation/admin-guide/mm/damon/start.rst | 96 ++++++
Documentation/admin-guide/mm/damon/usage.rst | 302 +++++++++++++++++++
Documentation/admin-guide/mm/index.rst | 1 +
Documentation/vm/damon/api.rst | 20 ++
Documentation/vm/damon/design.rst | 166 ++++++++++
Documentation/vm/damon/eval.rst | 222 ++++++++++++++
Documentation/vm/damon/faq.rst | 58 ++++
Documentation/vm/damon/index.rst | 31 ++
Documentation/vm/index.rst | 1 +
12 files changed, 1098 insertions(+)
create mode 100644 Documentation/admin-guide/mm/damon/guide.rst
create mode 100644 Documentation/admin-guide/mm/damon/index.rst
create mode 100644 Documentation/admin-guide/mm/damon/plans.rst
create mode 100644 Documentation/admin-guide/mm/damon/start.rst
create mode 100644 Documentation/admin-guide/mm/damon/usage.rst
create mode 100644 Documentation/vm/damon/api.rst
create mode 100644 Documentation/vm/damon/design.rst
create mode 100644 Documentation/vm/damon/eval.rst
create mode 100644 Documentation/vm/damon/faq.rst
create mode 100644 Documentation/vm/damon/index.rst
diff --git a/Documentation/admin-guide/mm/damon/guide.rst b/Documentation/admin-guide/mm/damon/guide.rst
new file mode 100644
index 000000000000..c51fb843efaa
--- /dev/null
+++ b/Documentation/admin-guide/mm/damon/guide.rst
@@ -0,0 +1,157 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+==================
+Optimization Guide
+==================
+
+This document helps you estimating the amount of benefit that you could get
+from DAMON-based optimizations, and describes how you could achieve it. You
+are assumed to already read :doc:`start`.
+
+
+Check The Signs
+===============
+
+No optimization can provide same extent of benefit to every case. Therefore
+you should first guess how much improvements you could get using DAMON. If
+some of below conditions match your situation, you could consider using DAMON.
+
+- *Low IPC and High Cache Miss Ratios.* Low IPC means most of the CPU time is
+ spent waiting for the completion of time-consuming operations such as memory
+ access, while high cache miss ratios mean the caches don't help it well.
+ DAMON is not for cache level optimization, but DRAM level. However,
+ improving DRAM management will also help this case by reducing the memory
+ operation latency.
+- *Memory Over-commitment and Unknown Users.* If you are doing memory
+ overcommitment and you cannot control every user of your system, a memory
+ bank run could happen at any time. You can estimate when it will happen
+ based on DAMON's monitoring results and act earlier to avoid or deal better
+ with the crisis.
+- *Frequent Memory Pressure.* Frequent memory pressure means your system has
+ wrong configurations or memory hogs. DAMON will help you find the right
+ configuration and/or the criminals.
+- *Heterogeneous Memory System.* If your system is utilizing memory devices
+ that placed between DRAM and traditional hard disks, such as non-volatile
+ memory or fast SSDs, DAMON could help you utilizing the devices more
+ efficiently.
+
+
+Profile
+=======
+
+If you found some positive signals, you could start by profiling your workloads
+using DAMON. Find major workloads on your systems and analyze their data
+access pattern to find something wrong or can be improved. The DAMON user
+space tool (``damo``) will be useful for this.
+
+We recommend you to start from working set size distribution check using ``damo
+report wss``. If the distribution is ununiform or quite different from what
+you estimated, you could consider `Memory Configuration`_ optimization.
+
+Then, review the overall access pattern in heatmap form using ``damo report
+heats``. If it shows a simple pattern consists of a small number of memory
+regions having high contrast of access temperature, you could consider manual
+`Program Modification`_.
+
+If you still want to absorb more benefits, you should develop `Personalized
+DAMON Application`_ for your special case.
+
+You don't need to take only one approach among the above plans, but you could
+use multiple of the above approaches to maximize the benefit.
+
+
+Optimize
+========
+
+If the profiling result also says it's worth trying some optimization, you
+could consider below approaches. Note that some of the below approaches assume
+that your systems are configured with swap devices or other types of auxiliary
+memory so that you don't strictly required to accommodate the whole working set
+in the main memory. Most of the detailed optimization should be made on your
+concrete understanding of your memory devices.
+
+
+Memory Configuration
+--------------------
+
+No more no less, DRAM should be large enough to accommodate only important
+working sets, because DRAM is highly performance critical but expensive and
+heavily consumes the power. However, knowing the size of the real important
+working sets is difficult. As a consequence, people usually equips
+unnecessarily large or too small DRAM. Many problems stem from such wrong
+configurations.
+
+Using the working set size distribution report provided by ``damo report wss``,
+you can know the appropriate DRAM size for you. For example, roughly speaking,
+if you worry about only 95 percentile latency, you don't need to equip DRAM of
+a size larger than 95 percentile working set size.
+
+Let's see a real example. This `page
+<https://damonitor.github.io/doc/html/v17/admin-guide/mm/damon/guide.html#memory-configuration>`_
+shows the heatmap and the working set size distributions/changes of
+``freqmine`` workload in PARSEC3 benchmark suite. The working set size spikes
+up to 180 MiB, but keeps smaller than 50 MiB for more than 95% of the time.
+Even though you give only 50 MiB of memory space to the workload, it will work
+well for 95% of the time. Meanwhile, you can save the 130 MiB of memory space.
+
+
+Program Modification
+--------------------
+
+If the data access pattern heatmap plotted by ``damo report heats`` is quite
+simple so that you can understand how the things are going in the workload with
+your human eye, you could manually optimize the memory management.
+
+For example, suppose that the workload has two big memory object but only one
+object is frequently accessed while the other one is only occasionally
+accessed. Then, you could modify the program source code to keep the hot
+object in the main memory by invoking ``mlock()`` or ``madvise()`` with
+``MADV_WILLNEED``. Or, you could proactively evict the cold object using
+``madvise()`` with ``MADV_COLD`` or ``MADV_PAGEOUT``. Using both together
+would be also worthy.
+
+A research work [1]_ using the ``mlock()`` achieved up to 2.55x performance
+speedup.
+
+Let's see another realistic example access pattern for this kind of
+optimizations. This `page
+<https://damonitor.github.io/doc/html/v17/admin-guide/mm/damon/guide.html#program-modification>`_
+shows the visualized access patterns of streamcluster workload in PARSEC3
+benchmark suite. We can easily identify the 100 MiB sized hot object.
+
+
+Personalized DAMON Application
+------------------------------
+
+Above approaches will work well for many general cases, but would not enough
+for some special cases.
+
+If this is the case, it might be the time to forget the comfortable use of the
+user space tool and dive into the debugfs interface (refer to :doc:`usage` for
+the detail) of DAMON. Using the interface, you can control the DAMON more
+flexibly. Therefore, you can write your personalized DAMON application that
+controls the monitoring via the debugfs interface, analyzes the result, and
+applies complex optimizations itself. Using this, you can make more creative
+and wise optimizations.
+
+If you are a kernel space programmer, writing kernel space DAMON applications
+using the API (refer to the :doc:`/vm/damon/api` for more detail) would be an
+option.
+
+
+Reference Practices
+===================
+
+Referencing previously done successful practices could help you getting the
+sense for this kind of optimizations. There is an academic paper [1]_
+reporting the visualized access pattern and manual `Program
+Modification`_ results for a number of realistic workloads. You can also get
+the visualized access patterns [3]_ [4]_ [5]_ and automated DAMON-based memory
+operations results for other realistic workloads that collected with latest
+version of DAMON [2]_ .
+
+.. [1] https://dl.acm.org/doi/10.1145/3366626.3368125
+.. [2] https://damonitor.github.io/test/result/perf/latest/html/
+.. [3] https://damonitor.github.io/test/result/visual/latest/rec.heatmap.1.png.html
+.. [4] https://damonitor.github.io/test/result/visual/latest/rec.wss_sz.png.html
+.. [5] https://damonitor.github.io/test/result/visual/latest/rec.wss_time.png.html
diff --git a/Documentation/admin-guide/mm/damon/index.rst b/Documentation/admin-guide/mm/damon/index.rst
new file mode 100644
index 000000000000..0baae7a5402b
--- /dev/null
+++ b/Documentation/admin-guide/mm/damon/index.rst
@@ -0,0 +1,15 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+========================
+Monitoring Data Accesses
+========================
+
+:doc:`DAMON </vm/damon/index>` allows light-weight data access monitoring.
+Using this, users can analyze and optimize their systems.
+
+.. toctree::
+ :maxdepth: 2
+
+ start
+ guide
+ usage
diff --git a/Documentation/admin-guide/mm/damon/plans.rst b/Documentation/admin-guide/mm/damon/plans.rst
new file mode 100644
index 000000000000..e3aa5ab96c29
--- /dev/null
+++ b/Documentation/admin-guide/mm/damon/plans.rst
@@ -0,0 +1,29 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+============
+Future Plans
+============
+
+DAMON is still on its first stage. Below plans are still under development.
+
+
+Automate Data Access Monitoring-based Memory Operation Schemes Execution
+========================================================================
+
+The ultimate goal of DAMON is to be used as a building block for the data
+access pattern aware kernel memory management optimization. It will make
+system just works efficiently. However, some users having very special
+workloads will want to further do their own optimization. DAMON will automate
+most of the tasks for such manual optimizations in near future. Users will be
+required to only describe what kind of data access pattern-based operation
+schemes they want in a simple form.
+
+By applying a very simple scheme for THP promotion/demotion with a prototype
+implementation, DAMON reduced 60% of THP memory footprint overhead while
+preserving 50% of the THP performance benefit. The detailed results can be
+seen on an external web page [1]_.
+
+Several RFC patchsets for this plan are available [2]_.
+
+.. [1] https://damonitor.github.io/test/result/perf/latest/html/
+.. [2] https://lore.kernel.org/linux-mm/[email protected]/
diff --git a/Documentation/admin-guide/mm/damon/start.rst b/Documentation/admin-guide/mm/damon/start.rst
new file mode 100644
index 000000000000..deed2ea2321e
--- /dev/null
+++ b/Documentation/admin-guide/mm/damon/start.rst
@@ -0,0 +1,96 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+===============
+Getting Started
+===============
+
+This document briefly describes how you can use DAMON by demonstrating its
+default user space tool. Please note that this document describes only a part
+of its features for brevity. Please refer to :doc:`usage` for more details.
+
+
+TL; DR
+======
+
+Follow below 5 commands to monitor and visualize the access pattern of your
+workload. ::
+
+ $ git clone https://github.com/sjp38/linux -b damon/master
+ /* build the kernel with CONFIG_DAMON=y, install, reboot */
+ $ mount -t debugfs none /sys/kernel/debug/
+ $ cd linux/tools/damon
+ $ ./damo record $(pidof <your workload>)
+ $ ./damo report heats --heatmap access_pattern.png
+
+
+Prerequisites
+=============
+
+Kernel
+------
+
+You should first ensure your system is running on a kernel built with
+``CONFIG_DAMON=y``.
+
+
+User Space Tool
+---------------
+
+For the demonstration, we will use the default user space tool for DAMON,
+called DAMON Operator (DAMO). It is located at ``tools/damon/damo`` of the
+kernel source tree. For brevity, below examples assume you set ``$PATH`` to
+point it. It's not mandatory, though.
+
+Because DAMO is using the debugfs interface (refer to :doc:`usage` for the
+detail) of DAMON, you should ensure debugfs is mounted. Mount it manually as
+below::
+
+ # mount -t debugfs none /sys/kernel/debug/
+
+or append below line to your ``/etc/fstab`` file so that your system can
+automatically mount debugfs from next booting::
+
+ debugfs /sys/kernel/debug debugfs defaults 0 0
+
+
+Recording Data Access Patterns
+==============================
+
+Below commands record memory access pattern of a program and save the
+monitoring results in a file. ::
+
+ $ git clone https://github.com/sjp38/masim
+ $ cd masim; make; ./masim ./configs/zigzag.cfg &
+ $ sudo damo record -o damon.data $(pidof masim)
+
+The first two lines of the commands get an artificial memory access generator
+program and runs it in the background. It will repeatedly access two 100 MiB
+sized memory regions one by one. You can substitute this with your real
+workload. The last line asks ``damo`` to record the access pattern in
+``damon.data`` file.
+
+
+Visualizing Recorded Patterns
+=============================
+
+Below three commands visualize the recorded access patterns into three
+image files. ::
+
+ $ damo report heats --heatmap access_pattern_heatmap.png
+ $ damo report wss --range 0 101 1 --plot wss_dist.png
+ $ damo report wss --range 0 101 1 --sortby time --plot wss_chron_change.png
+
+- ``access_pattern_heatmap.png`` will show the data access pattern in a
+ heatmap, which shows when (x-axis) what memory region (y-axis) is how
+ frequently accessed (color).
+- ``wss_dist.png`` will show the distribution of the working set size.
+- ``wss_chron_change.png`` will show how the working set size has
+ chronologically changed.
+
+You can show the images in a web page [1]_ . Those made with other realistic
+workloads are also available [2]_ [3]_ [4]_.
+
+.. [1] https://damonitor.github.io/doc/html/v17/admin-guide/mm/damon/start.html#visualizing-recorded-patterns
+.. [2] https://damonitor.github.io/test/result/visual/latest/rec.heatmap.1.png.html
+.. [3] https://damonitor.github.io/test/result/visual/latest/rec.wss_sz.png.html
+.. [4] https://damonitor.github.io/test/result/visual/latest/rec.wss_time.png.html
diff --git a/Documentation/admin-guide/mm/damon/usage.rst b/Documentation/admin-guide/mm/damon/usage.rst
new file mode 100644
index 000000000000..a6606d27a559
--- /dev/null
+++ b/Documentation/admin-guide/mm/damon/usage.rst
@@ -0,0 +1,302 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+===============
+Detailed Usages
+===============
+
+DAMON provides below three interfaces for different users.
+
+- *DAMON user space tool.*
+ This is for privileged people such as system administrators who want a
+ just-working human-friendly interface. Using this, users can use the DAMON’s
+ major features in a human-friendly way. It may not be highly tuned for
+ special cases, though. It supports only virtual address spaces monitoring.
+- *debugfs interface.*
+ This is for privileged user space programmers who want more optimized use of
+ DAMON. Using this, users can use DAMON’s major features by reading
+ from and writing to special debugfs files. Therefore, you can write and use
+ your personalized DAMON debugfs wrapper programs that reads/writes the
+ debugfs files instead of you. The DAMON user space tool is also a reference
+ implementation of such programs. It supports only virtual address spaces
+ monitoring.
+- *Kernel Space Programming Interface.*
+ This is for kernel space programmers. Using this, users can utilize every
+ feature of DAMON most flexibly and efficiently by writing kernel space
+ DAMON application programs for you. You can even extend DAMON for various
+ address spaces.
+
+This document does not describe the kernel space programming interface in
+detail. For that, please refer to the :doc:`/vm/damon/api`.
+
+
+DAMON User Space Tool
+=====================
+
+A reference implementation of the DAMON user space tools which provides a
+convenient user interface is in the kernel source tree. It is located at
+``tools/damon/damo`` of the tree.
+
+The tool provides a subcommands based interface. Every subcommand provides
+``-h`` option, which provides the minimal usage of it. Currently, the tool
+supports two subcommands, ``record`` and ``report``.
+
+Below example commands assume you set ``$PATH`` to point ``tools/damon/`` for
+brevity. It is not mandatory for use of ``damo``, though.
+
+
+Recording Data Access Pattern
+-----------------------------
+
+The ``record`` subcommand records the data access pattern of target workloads
+in a file (``./damon.data`` by default). You can specify the target with 1)
+the command for execution of the monitoring target process, or 2) pid of
+running target process. Below example shows a command target usage::
+
+ # cd <kernel>/tools/damon/
+ # damo record "sleep 5"
+
+The tool will execute ``sleep 5`` by itself and record the data access patterns
+of the process. Below example shows a pid target usage::
+
+ # sleep 5 &
+ # damo record `pidof sleep`
+
+The location of the recorded file can be explicitly set using ``-o`` option.
+You can further tune this by setting the monitoring attributes. To know about
+the monitoring attributes in detail, please refer to the
+:doc:`/vm/damon/design`.
+
+
+Analyzing Data Access Pattern
+-----------------------------
+
+The ``report`` subcommand reads a data access pattern record file (if not
+explicitly specified using ``-i`` option, reads ``./damon.data`` file by
+default) and generates human-readable reports. You can specify what type of
+report you want using a sub-subcommand to ``report`` subcommand. ``raw``,
+``heats``, and ``wss`` report types are supported for now.
+
+
+raw
+~~~
+
+``raw`` sub-subcommand simply transforms the binary record into a
+human-readable text. For example::
+
+ $ damo report raw
+ start_time: 193485829398
+ rel time: 0
+ nr_tasks: 1
+ target_id: 1348
+ nr_regions: 4
+ 560189609000-56018abce000( 22827008): 0
+ 7fbdff59a000-7fbdffaf1a00( 5601792): 0
+ 7fbdffaf1a00-7fbdffbb5000( 800256): 1
+ 7ffea0dc0000-7ffea0dfd000( 249856): 0
+
+ rel time: 100000731
+ nr_tasks: 1
+ target_id: 1348
+ nr_regions: 6
+ 560189609000-56018abce000( 22827008): 0
+ 7fbdff59a000-7fbdff8ce933( 3361075): 0
+ 7fbdff8ce933-7fbdffaf1a00( 2240717): 1
+ 7fbdffaf1a00-7fbdffb66d99( 480153): 0
+ 7fbdffb66d99-7fbdffbb5000( 320103): 1
+ 7ffea0dc0000-7ffea0dfd000( 249856): 0
+
+The first line shows the recording started timestamp (nanosecond). Records of
+data access patterns follows. Each record is separated by a blank line. Each
+record first specifies the recorded time (``rel time``) in relative to the
+start time, the number of monitored tasks in this record (``nr_tasks``).
+Recorded data access patterns of each task follow. Each data access pattern
+for each task shows the target's pid (``target_id``) and a number of monitored
+address regions in this access pattern (``nr_regions``) first. After that,
+each line shows the start/end address, size, and the number of observed
+accesses of each region.
+
+
+heats
+~~~~~
+
+The ``raw`` output is very detailed but hard to manually read. ``heats``
+sub-subcommand plots the data in 3-dimensional form, which represents the time
+in x-axis, address of regions in y-axis, and the access frequency in z-axis.
+Users can set the resolution of the map (``--tres`` and ``--ares``) and
+start/end point of each axis (``--tmin``, ``--tmax``, ``--amin``, and
+``--amax``) via optional arguments. For example::
+
+ $ damo report heats --tres 3 --ares 3
+ 0 0 0.0
+ 0 7609002 0.0
+ 0 15218004 0.0
+ 66112620851 0 0.0
+ 66112620851 7609002 0.0
+ 66112620851 15218004 0.0
+ 132225241702 0 0.0
+ 132225241702 7609002 0.0
+ 132225241702 15218004 0.0
+
+This command shows a recorded access pattern in heatmap of 3x3 resolution.
+Therefore it shows 9 data points in total. Each line shows each of the data
+points. The three numbers in each line represent time in nanosecond, address,
+and the observed access frequency.
+
+Users will be able to convert this text output into a heatmap image (represents
+z-axis values with colors) or other 3D representations using various tools such
+as 'gnuplot'. For more convenience, ``heats`` sub-subcommand provides the
+'gnuplot' based heatmap image creation. For this, you can use ``--heatmap``
+option. Also, note that because it uses 'gnuplot' internally, it will fail if
+'gnuplot' is not installed on your system. For example::
+
+ $ ./damo report heats --heatmap heatmap.png
+
+Creates the heatmap image in ``heatmap.png`` file. It supports ``pdf``,
+``png``, ``jpeg``, and ``svg``.
+
+If the target address space is virtual memory address space and you plot the
+entire address space, the huge unmapped regions will make the picture looks
+only black. Therefore you should do proper zoom in / zoom out using the
+resolution and axis boundary-setting arguments. To make this effort minimal,
+you can use ``--guide`` option as below::
+
+ $ ./damo report heats --guide
+ target_id:1348
+ time: 193485829398-198337863555 (4852034157)
+ region 0: 00000094564599762944-00000094564622589952 (22827008)
+ region 1: 00000140454009610240-00000140454016012288 (6402048)
+ region 2: 00000140731597193216-00000140731597443072 (249856)
+
+The output shows unions of monitored regions (start and end addresses in byte)
+and the union of monitored time duration (start and end time in nanoseconds) of
+each target task. Therefore, it would be wise to plot the data points in each
+union. If no axis boundary option is given, it will automatically find the
+biggest union in ``--guide`` output and set the boundary in it.
+
+
+wss
+~~~
+
+The ``wss`` type extracts the distribution and chronological working set size
+changes from the records. For example::
+
+ $ ./damo report wss
+ # <percentile> <wss>
+ # target_id 1348
+ # avr: 66228
+ 0 0
+ 25 0
+ 50 0
+ 75 0
+ 100 1920615
+
+Without any option, it shows the distribution of the working set sizes as
+above. It shows 0th, 25th, 50th, 75th, and 100th percentile and the average of
+the measured working set sizes in the access pattern records. In this case,
+the working set size was zero for 75th percentile but 1,920,615 bytes in max
+and 66,228 bytes on average.
+
+By setting the sort key of the percentile using '--sortby', you can show how
+the working set size has chronologically changed. For example::
+
+ $ ./damo report wss --sortby time
+ # <percentile> <wss>
+ # target_id 1348
+ # avr: 66228
+ 0 0
+ 25 0
+ 50 0
+ 75 0
+ 100 0
+
+The average is still 66,228. And, because the access was spiked in very short
+duration and this command plots only 4 data points, we cannot show when the
+access spikes made. Users can specify the resolution of the distribution
+(``--range``). By giving more fine resolution, the short duration spikes could
+be found.
+
+Similar to that of ``heats --heatmap``, it also supports 'gnuplot' based simple
+visualization of the distribution via ``--plot`` option.
+
+
+debugfs Interface
+=================
+
+DAMON exports four files, ``attrs``, ``target_ids``, ``record``, and
+``monitor_on`` under its debugfs directory, ``<debugfs>/damon/``.
+
+
+Attributes
+----------
+
+Users can get and set the ``sampling interval``, ``aggregation interval``,
+``regions update interval``, and min/max number of monitoring target regions by
+reading from and writing to the ``attrs`` file. To know about the monitoring
+attributes in detail, please refer to the :doc:`/vm/damon/design`. For
+example, below commands set those values to 5 ms, 100 ms, 1,000 ms, 10 and
+1000, and then check it again::
+
+ # cd <debugfs>/damon
+ # echo 5000 100000 1000000 10 1000 > attrs
+ # cat attrs
+ 5000 100000 1000000 10 1000
+
+
+Target IDs
+----------
+
+Some types of address spaces supports multiple monitoring target. For example,
+the virtual memory address spaces monitoring can have multiple processes as the
+monitoring targets. Users can set the targets by writing relevant id values of
+the targets to, and get the ids of the current targets by reading from the
+``target_ids`` file. In case of the virtual address spaces monitoring, the
+values should be pids of the monitoring target processes. For example, below
+commands set processes having pids 42 and 4242 as the monitoring targets and
+check it again::
+
+ # cd <debugfs>/damon
+ # echo 42 4242 > target_ids
+ # cat target_ids
+ 42 4242
+
+Note that setting the target ids doesn't start the monitoring.
+
+
+Record
+------
+
+This debugfs file allows you to record monitored access patterns in a regular
+binary file. The recorded results are first written in an in-memory buffer and
+flushed to a file in batch. Users can get and set the size of the buffer and
+the path to the result file by reading from and writing to the ``record`` file.
+For example, below commands set the buffer to be 4 KiB and the result to be
+saved in ``/damon.data``. ::
+
+ # cd <debugfs>/damon
+ # echo "4096 /damon.data" > record
+ # cat record
+ 4096 /damon.data
+
+The recording can be disabled by setting the buffer size zero.
+
+
+Turning On/Off
+--------------
+
+Setting the files as described above doesn't incur effect unless you explicitly
+start the monitoring. You can start, stop, and check the current status of the
+monitoring by writing to and reading from the ``monitor_on`` file. Writing
+``on`` to the file starts the monitoring of the targets with the attributes.
+Writing ``off`` to the file stops those. DAMON also stops if every target
+process is terminated. Below example commands turn on, off, and check the
+status of DAMON::
+
+ # cd <debugfs>/damon
+ # echo on > monitor_on
+ # echo off > monitor_on
+ # cat monitor_on
+ off
+
+Please note that you cannot write to the above-mentioned debugfs files while
+the monitoring is turned on. If you write to the files while DAMON is running,
+an error code such as ``-EBUSY`` will be returned.
diff --git a/Documentation/admin-guide/mm/index.rst b/Documentation/admin-guide/mm/index.rst
index 11db46448354..e6de5cd41945 100644
--- a/Documentation/admin-guide/mm/index.rst
+++ b/Documentation/admin-guide/mm/index.rst
@@ -27,6 +27,7 @@ the Linux memory management.
concepts
cma_debugfs
+ damon/index
hugetlbpage
idle_page_tracking
ksm
diff --git a/Documentation/vm/damon/api.rst b/Documentation/vm/damon/api.rst
new file mode 100644
index 000000000000..649409828eab
--- /dev/null
+++ b/Documentation/vm/damon/api.rst
@@ -0,0 +1,20 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=============
+API Reference
+=============
+
+Kernel space programs can use every feature of DAMON using below APIs. All you
+need to do is including ``damon.h``, which is located in ``include/linux/`` of
+the source tree.
+
+Structures
+==========
+
+.. kernel-doc:: include/linux/damon.h
+
+
+Functions
+=========
+
+.. kernel-doc:: mm/damon.c
diff --git a/Documentation/vm/damon/design.rst b/Documentation/vm/damon/design.rst
new file mode 100644
index 000000000000..727d72093f8f
--- /dev/null
+++ b/Documentation/vm/damon/design.rst
@@ -0,0 +1,166 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+======
+Design
+======
+
+Configurable Layers
+===================
+
+DAMON provides data access monitoring functionality while making the accuracy
+and the overhead controllable. The fundamental access monitorings require
+primitives that dependent on and optimized for the target address space. On
+the other hand, the accuracy and overhead tradeoff mechanism, which is the core
+of DAMON, is in the pure logic space. DAMON separates the two parts in
+different layers and defines its interface to allow various low level
+primitives implementations configurable with the core logic.
+
+Due to this separated design and the configurable interface, users can extend
+DAMON for any address space by configuring the core logics with appropriate low
+level primitive implementations. If appropriate one is not provided, users can
+implement the primitives on their own.
+
+For example, physical memory, virtual memory, swap space, those for specific
+processes, NUMA nodes, files, and backing memory devices would be supportable.
+Also, if some architectures or devices support special optimized access check
+primitives, those will be easily configurable.
+
+
+Reference Implementations of Address Space Specific Primitives
+==============================================================
+
+The low level primitives for the fundamental access monitoring are defined in
+two parts:
+
+1. Identification of the monitoring target address range for the address space.
+2. Access check of specific address range in the target space.
+
+DAMON currently provides the implementation of the primitives for only the
+virtual address spaces. Below two subsections describe how it works.
+
+
+PTE Accessed-bit Based Access Check
+-----------------------------------
+
+The implementation for the virtual address space uses PTE Accessed-bit for
+basic access checks. It finds the relevant PTE Accessed bit from the address
+by walking the page table for the target task of the address. In this way, the
+implementation finds and clears the bit for next sampling target address and
+checks whether the bit set again after one sampling period. This could disturb
+other kernel subsystems using the Accessed bits, namely Idle page tracking and
+the reclaim logic. To avoid such disturbances, DAMON makes it mutually
+exclusive with Idle page tracking and uses ``PG_idle`` and ``PG_young`` page
+flags to solve the conflict with the reclaim logic, as Idle page tracking does.
+
+
+VMA-based Target Address Range Construction
+-------------------------------------------
+
+Only small parts in the super-huge virtual address space of the processes are
+mapped to the physical memory and accessed. Thus, tracking the unmapped
+address regions is just wasteful. However, because DAMON can deal with some
+level of noise using the adaptive regions adjustment mechanism, tracking every
+mapping is not strictly required but could even incur a high overhead in some
+cases. That said, too huge unmapped areas inside the monitoring target should
+be removed to not take the time for the adaptive mechanism.
+
+For the reason, this implementation converts the complex mappings to three
+distinct regions that cover every mapped area of the address space. The two
+gaps between the three regions are the two biggest unmapped areas in the given
+address space. The two biggest unmapped areas would be the gap between the
+heap and the uppermost mmap()-ed region, and the gap between the lowermost
+mmap()-ed region and the stack in most of the cases. Because these gaps are
+exceptionally huge in usual address spaces, excluding these will be sufficient
+to make a reasonable trade-off. Below shows this in detail::
+
+ <heap>
+ <BIG UNMAPPED REGION 1>
+ <uppermost mmap()-ed region>
+ (small mmap()-ed regions and munmap()-ed regions)
+ <lowermost mmap()-ed region>
+ <BIG UNMAPPED REGION 2>
+ <stack>
+
+
+Address Space Independent Core Mechanisms
+=========================================
+
+Below four sections describe each of the DAMON core mechanisms and the five
+monitoring attributes, ``sampling interval``, ``aggregation interval``,
+``regions update interval``, ``minimum number of regions``, and ``maximum
+number of regions``.
+
+
+Access Frequency Monitoring
+---------------------------
+
+The output of DAMON says what pages are how frequently accessed for a given
+duration. The resolution of the access frequency is controlled by setting
+``sampling interval`` and ``aggregation interval``. In detail, DAMON checks
+access to each page per ``sampling interval`` and aggregates the results. In
+other words, counts the number of the accesses to each page. After each
+``aggregation interval`` passes, DAMON calls callback functions that previously
+registered by users so that users can read the aggregated results and then
+clears the results. This can be described in below simple pseudo-code::
+
+ while monitoring_on:
+ for page in monitoring_target:
+ if accessed(page):
+ nr_accesses[page] += 1
+ if time() % aggregation_interval == 0:
+ for callback in user_registered_callbacks:
+ callback(monitoring_target, nr_accesses)
+ for page in monitoring_target:
+ nr_accesses[page] = 0
+ sleep(sampling interval)
+
+The monitoring overhead of this mechanism will arbitrarily increase as the
+size of the target workload grows.
+
+
+Region Based Sampling
+---------------------
+
+To avoid the unbounded increase of the overhead, DAMON groups adjacent pages
+that assumed to have the same access frequencies into a region. As long as the
+assumption (pages in a region have the same access frequencies) is kept, only
+one page in the region is required to be checked. Thus, for each ``sampling
+interval``, DAMON randomly picks one page in each region, waits for one
+``sampling interval``, checks whether the page is accessed meanwhile, and
+increases the access frequency of the region if so. Therefore, the monitoring
+overhead is controllable by setting the number of regions. DAMON allows users
+to set the minimum and the maximum number of regions for the trade-off.
+
+This scheme, however, cannot preserve the quality of the output if the
+assumption is not guaranteed.
+
+
+Adaptive Regions Adjustment
+---------------------------
+
+Even somehow the initial monitoring target regions are well constructed to
+fulfill the assumption (pages in same region have similar access frequencies),
+the data access pattern can be dynamically changed. This will result in low
+monitoring quality. To keep the assumption as much as possible, DAMON
+adaptively merges and splits each region based on their access frequency.
+
+For each ``aggregation interval``, it compares the access frequencies of
+adjacent regions and merges those if the frequency difference is small. Then,
+after it reports and clears the aggregated access frequency of each region, it
+splits each region into two or three regions if the total number of regions
+will not exceed the user-specified maximum number of regions after the split.
+
+In this way, DAMON provides its best-effort quality and minimal overhead while
+keeping the bounds users set for their trade-off.
+
+
+Dynamic Target Space Updates Handling
+-------------------------------------
+
+The monitoring target address range could dynamically changed. For example,
+virtual memory could be dynamically mapped and unmapped. Physical memory could
+be hot-plugged.
+
+As the changes could be quite frequent in some cases, DAMON checks the dynamic
+memory mapping changes and applies it to the abstracted target area only for
+each of a user-specified time interval (``regions update interval``).
diff --git a/Documentation/vm/damon/eval.rst b/Documentation/vm/damon/eval.rst
new file mode 100644
index 000000000000..b233890b4e45
--- /dev/null
+++ b/Documentation/vm/damon/eval.rst
@@ -0,0 +1,222 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+==========
+Evaluation
+==========
+
+DAMON is lightweight. It increases system memory usage by only -0.25% and
+consumes less than 1% CPU time in most case. It slows target workloads down by
+only 0.94%.
+
+DAMON is accurate and useful for memory management optimizations. An
+experimental DAMON-based operation scheme for THP, 'ethp', removes 31.29% of
+THP memory overheads while preserving 60.64% of THP speedup. Another
+experimental DAMON-based 'proactive reclamation' implementation, 'prcl',
+reduces 87.95% of residential sets and 29.52% of system memory footprint while
+incurring only 2.15% runtime overhead in the best case (parsec3/freqmine).
+
+Setup
+=====
+
+On a QEMU/KVM based virtual machine utilizing 20GB of RAM and hosted by an
+Intel i7 machine that running a kernel that v16 DAMON patchset is applied, I
+measure runtime and consumed system memory while running various realistic
+workloads with several configurations. I use 13 and 12 workloads in PARSEC3
+[3]_ and SPLASH-2X [4]_ benchmark suites, respectively. I use another wrapper
+scripts [5]_ for convenient setup and run of the workloads.
+
+Measurement
+-----------
+
+For the measurement of the amount of consumed memory in system global scope, I
+drop caches before starting each of the workloads and monitor 'MemFree' in the
+'/proc/meminfo' file. To make results more stable, I repeat the runs 5 times
+and average results.
+
+Configurations
+--------------
+
+The configurations I use are as below.
+
+- orig: Linux v5.7 with 'madvise' THP policy
+- rec: 'orig' plus DAMON running with virtual memory access recording
+- prec: 'orig' plus DAMON running with physical memory access recording
+- thp: same with 'orig', but use 'always' THP policy
+- ethp: 'orig' plus a DAMON operation scheme, 'efficient THP'
+- prcl: 'orig' plus a DAMON operation scheme, 'proactive reclaim [6]_'
+
+I use 'rec' for measurement of DAMON overheads to target workloads and system
+memory. 'prec' is for physical memory monitroing and recording. It monitors
+17GB sized 'System RAM' region. The remaining configs including 'thp', 'ethp',
+and 'prcl' are for measurement of DAMON monitoring accuracy.
+
+'ethp' and 'prcl' are simple DAMON-based operation schemes developed for
+proof of concepts of DAMON. 'ethp' reduces memory space waste of THP by using
+DAMON for the decision of promotions and demotion for huge pages, while 'prcl'
+is as similar as the original work. Those are implemented as below::
+
+ # format: <min/max size> <min/max frequency (0-100)> <min/max age> <action>
+ # ethp: Use huge pages if a region shows >=5% access rate, use regular
+ # pages if a region >=2MB shows <5% access rate for >=13 seconds
+ null null 5 null null null hugepage
+ 2M null null null 13s null nohugepage
+
+ # prcl: If a region >=4KB shows <=5% access rate for >=7 seconds, page out.
+ 4K null null 5 7s null pageout
+
+Note that both 'ethp' and 'prcl' are designed with my only straightforward
+intuition because those are for only proof of concepts and monitoring accuracy
+of DAMON. In other words, those are not for production. For production use,
+those should be more tuned.
+
+.. [1] "Redis latency problems troubleshooting", https://redis.io/topics/latency
+.. [2] "Disable Transparent Huge Pages (THP)",
+ https://docs.mongodb.com/manual/tutorial/transparent-huge-pages/
+.. [3] "The PARSEC Becnhmark Suite", https://parsec.cs.princeton.edu/index.htm
+.. [4] "SPLASH-2x", https://parsec.cs.princeton.edu/parsec3-doc.htm#splash2x
+.. [5] "parsec3_on_ubuntu", https://github.com/sjp38/parsec3_on_ubuntu
+.. [6] "Proactively reclaiming idle memory", https://lwn.net/Articles/787611/
+
+Results
+=======
+
+Below two tables show the measurement results. The runtimes are in seconds
+while the memory usages are in KiB. Each configuration except 'orig' shows
+its overhead relative to 'orig' in percent within parenthesizes.::
+
+ runtime orig rec (overhead) prec (overhead) thp (overhead) ethp (overhead) prcl (overhead)
+ parsec3/blackscholes 107.228 107.859 (0.59) 108.110 (0.82) 107.381 (0.14) 106.811 (-0.39) 114.766 (7.03)
+ parsec3/bodytrack 79.292 79.609 (0.40) 79.777 (0.61) 79.313 (0.03) 78.892 (-0.50) 80.398 (1.40)
+ parsec3/canneal 148.887 150.878 (1.34) 153.337 (2.99) 127.873 (-14.11) 132.272 (-11.16) 167.631 (12.59)
+ parsec3/dedup 11.970 11.975 (0.04) 12.024 (0.45) 11.752 (-1.82) 11.921 (-0.41) 13.244 (10.64)
+ parsec3/facesim 212.800 215.927 (1.47) 215.004 (1.04) 205.117 (-3.61) 207.401 (-2.54) 220.834 (3.78)
+ parsec3/ferret 190.646 192.560 (1.00) 192.414 (0.93) 190.662 (0.01) 192.309 (0.87) 193.497 (1.50)
+ parsec3/fluidanimate 213.951 216.459 (1.17) 217.578 (1.70) 209.500 (-2.08) 211.826 (-0.99) 218.299 (2.03)
+ parsec3/freqmine 291.050 292.117 (0.37) 293.279 (0.77) 289.553 (-0.51) 291.768 (0.25) 297.309 (2.15)
+ parsec3/raytrace 118.645 119.734 (0.92) 119.521 (0.74) 117.715 (-0.78) 118.844 (0.17) 134.045 (12.98)
+ parsec3/streamcluster 332.843 336.997 (1.25) 337.049 (1.26) 279.716 (-15.96) 290.985 (-12.58) 346.646 (4.15)
+ parsec3/swaptions 155.437 157.174 (1.12) 156.159 (0.46) 155.017 (-0.27) 154.955 (-0.31) 156.555 (0.72)
+ parsec3/vips 59.215 59.426 (0.36) 59.156 (-0.10) 59.243 (0.05) 58.858 (-0.60) 60.184 (1.64)
+ parsec3/x264 67.445 71.400 (5.86) 71.122 (5.45) 64.078 (-4.99) 66.027 (-2.10) 71.489 (6.00)
+ splash2x/barnes 81.826 81.800 (-0.03) 82.648 (1.00) 74.343 (-9.15) 79.063 (-3.38) 103.785 (26.84)
+ splash2x/fft 33.850 34.148 (0.88) 33.912 (0.18) 23.493 (-30.60) 32.684 (-3.44) 48.303 (42.70)
+ splash2x/lu_cb 86.404 86.333 (-0.08) 86.988 (0.68) 85.720 (-0.79) 85.944 (-0.53) 89.338 (3.40)
+ splash2x/lu_ncb 94.908 98.021 (3.28) 96.041 (1.19) 90.304 (-4.85) 93.279 (-1.72) 97.270 (2.49)
+ splash2x/ocean_cp 47.122 47.391 (0.57) 47.902 (1.65) 43.227 (-8.26) 44.609 (-5.33) 51.410 (9.10)
+ splash2x/ocean_ncp 93.147 92.911 (-0.25) 93.886 (0.79) 51.451 (-44.76) 71.107 (-23.66) 112.554 (20.83)
+ splash2x/radiosity 92.150 92.604 (0.49) 93.339 (1.29) 90.802 (-1.46) 91.824 (-0.35) 104.439 (13.34)
+ splash2x/radix 31.961 32.113 (0.48) 32.066 (0.33) 25.184 (-21.20) 30.412 (-4.84) 49.989 (56.41)
+ splash2x/raytrace 84.781 85.278 (0.59) 84.763 (-0.02) 83.192 (-1.87) 83.970 (-0.96) 85.382 (0.71)
+ splash2x/volrend 87.401 87.978 (0.66) 87.977 (0.66) 86.636 (-0.88) 87.169 (-0.26) 88.043 (0.73)
+ splash2x/water_nsquared 239.140 239.570 (0.18) 240.901 (0.74) 221.323 (-7.45) 224.670 (-6.05) 244.492 (2.24)
+ splash2x/water_spatial 89.538 89.978 (0.49) 90.171 (0.71) 89.729 (0.21) 89.238 (-0.34) 99.331 (10.94)
+ total 3051.620 3080.230 (0.94) 3085.130 (1.10) 2862.320 (-6.20) 2936.830 (-3.76) 3249.240 (6.48)
+
+
+ memused.avg orig rec (overhead) prec (overhead) thp (overhead) ethp (overhead) prcl (overhead)
+ parsec3/blackscholes 1676679.200 1683789.200 (0.42) 1680281.200 (0.21) 1613817.400 (-3.75) 1835229.200 (9.46) 1407952.800 (-16.03)
+ parsec3/bodytrack 1295736.000 1308412.600 (0.98) 1311988.000 (1.25) 1243417.400 (-4.04) 1435410.600 (10.78) 1255566.400 (-3.10)
+ parsec3/canneal 1004062.000 1008823.800 (0.47) 1000100.200 (-0.39) 983976.000 (-2.00) 1051719.600 (4.75) 993055.800 (-1.10)
+ parsec3/dedup 2389765.800 2393381.000 (0.15) 2366668.200 (-0.97) 2412948.600 (0.97) 2435885.600 (1.93) 2380172.800 (-0.40)
+ parsec3/facesim 488927.200 498228.000 (1.90) 496683.800 (1.59) 476327.800 (-2.58) 552890.000 (13.08) 449143.600 (-8.14)
+ parsec3/ferret 280324.600 282032.400 (0.61) 282284.400 (0.70) 258211.000 (-7.89) 331493.800 (18.25) 265850.400 (-5.16)
+ parsec3/fluidanimate 560636.200 569038.200 (1.50) 565067.400 (0.79) 556923.600 (-0.66) 588021.200 (4.88) 512901.600 (-8.51)
+ parsec3/freqmine 883286.000 904960.200 (2.45) 886105.200 (0.32) 849347.400 (-3.84) 998358.000 (13.03) 622542.800 (-29.52)
+ parsec3/raytrace 1639370.200 1642318.200 (0.18) 1626673.200 (-0.77) 1591284.200 (-2.93) 1755088.400 (7.06) 1410261.600 (-13.98)
+ parsec3/streamcluster 116955.600 127251.400 (8.80) 121441.000 (3.84) 113853.800 (-2.65) 139659.400 (19.41) 120335.200 (2.89)
+ parsec3/swaptions 8342.400 18555.600 (122.43) 16581.200 (98.76) 6745.800 (-19.14) 27487.200 (229.49) 14275.600 (71.12)
+ parsec3/vips 2776417.600 2784989.400 (0.31) 2820564.600 (1.59) 2694060.800 (-2.97) 2968650.000 (6.92) 2713590.000 (-2.26)
+ parsec3/x264 2912885.000 2936474.600 (0.81) 2936775.800 (0.82) 2799599.200 (-3.89) 3168695.000 (8.78) 2829085.800 (-2.88)
+ splash2x/barnes 1206459.600 1204145.600 (-0.19) 1177390.000 (-2.41) 1210556.800 (0.34) 1214978.800 (0.71) 907737.000 (-24.76)
+ splash2x/fft 9384156.400 9258749.600 (-1.34) 8560377.800 (-8.78) 9337563.000 (-0.50) 9228873.600 (-1.65) 9823394.400 (4.68)
+ splash2x/lu_cb 510210.800 514052.800 (0.75) 502735.200 (-1.47) 514459.800 (0.83) 523884.200 (2.68) 367563.200 (-27.96)
+ splash2x/lu_ncb 510091.200 516046.800 (1.17) 505327.600 (-0.93) 512568.200 (0.49) 524178.400 (2.76) 427981.800 (-16.10)
+ splash2x/ocean_cp 3342260.200 3294531.200 (-1.43) 3171236.000 (-5.12) 3379693.600 (1.12) 3314896.600 (-0.82) 3252406.000 (-2.69)
+ splash2x/ocean_ncp 3900447.200 3881682.600 (-0.48) 3816493.200 (-2.15) 7065506.200 (81.15) 4449224.400 (14.07) 3829931.200 (-1.81)
+ splash2x/radiosity 1466372.000 1463840.200 (-0.17) 1438554.000 (-1.90) 1475151.600 (0.60) 1474828.800 (0.58) 496636.000 (-66.13)
+ splash2x/radix 1760056.600 1691719.000 (-3.88) 1613057.400 (-8.35) 1384416.400 (-21.34) 1632274.400 (-7.26) 2141640.200 (21.68)
+ splash2x/raytrace 38794.000 48187.400 (24.21) 46728.400 (20.45) 41323.400 (6.52) 61499.800 (58.53) 68455.200 (76.46)
+ splash2x/volrend 138107.400 148197.000 (7.31) 146223.400 (5.88) 128076.400 (-7.26) 164593.800 (19.18) 140885.200 (2.01)
+ splash2x/water_nsquared 39072.000 49889.200 (27.69) 47548.400 (21.69) 37546.400 (-3.90) 57195.400 (46.38) 42994.200 (10.04)
+ splash2x/water_spatial 662099.800 665964.800 (0.58) 651017.000 (-1.67) 659808.400 (-0.35) 674475.600 (1.87) 519677.600 (-21.51)
+ total 38991500.000 38895300.000 (-0.25) 37787817.000 (-3.09) 41347200.000 (6.04) 40609600.000 (4.15) 36994100.000 (-5.12)
+
+
+DAMON Overheads
+---------------
+
+In total, DAMON virtual memory access recording feature ('rec') incurs 0.94%
+runtime overhead and -0.25% memory space overhead. Even though the size of the
+monitoring target region becomes much larger with the physical memory access
+recording ('prec'), it still shows only modest amount of overhead (1.10% for
+runtime and -3.09% for memory footprint).
+
+For a convenience test run of 'rec' and 'prec', I use a Python wrapper. The
+wrapper constantly consumes about 10-15MB of memory. This becomes a high
+memory overhead if the target workload has a small memory footprint.
+Nonetheless, the overheads are not from DAMON, but from the wrapper, and thus
+should be ignored. This fake memory overhead continues in 'ethp' and 'prcl',
+as those configurations are also using the Python wrapper.
+
+
+Efficient THP
+-------------
+
+THP 'always' enabled policy achieves 6.20% speedup but incurs 6.04% memory
+overhead. It achieves 44.76% speedup in the best case, but 81.15% memory
+overhead in the worst case. Interestingly, both the best and worst-case are
+with 'splash2x/ocean_ncp').
+
+The 2-lines implementation of data access monitoring based THP version ('ethp')
+shows 3.76% speedup and 4.15% memory overhead. In other words, 'ethp' removes
+31.29% of THP memory waste while preserving 60.64% of THP speedup in total. In
+the case of the 'splash2x/ocean_ncp', 'ethp' removes 82.66% of THP memory waste
+while preserving 52.85% of THP speedup.
+
+
+Proactive Reclamation
+---------------------
+
+As similar to the original work, I use 4G 'zram' swap device for this
+configuration.
+
+In total, our 1 line implementation of Proactive Reclamation, 'prcl', incurred
+6.48% runtime overhead in total while achieving 5.12% system memory usage
+reduction.
+
+Nonetheless, as the memory usage is calculated with 'MemFree' in
+'/proc/meminfo', it contains the SwapCached pages. As the swapcached pages can
+be easily evicted, I also measured the residential set size of the workloads::
+
+ rss.avg orig rec (overhead) prec (overhead) thp (overhead) ethp (overhead) prcl (overhead)
+ parsec3/blackscholes 590412.200 589991.400 (-0.07) 591716.400 (0.22) 591131.000 (0.12) 591055.200 (0.11) 274623.600 (-53.49)
+ parsec3/bodytrack 32202.200 32297.400 (0.30) 32301.400 (0.31) 32328.000 (0.39) 32169.800 (-0.10) 25311.200 (-21.40)
+ parsec3/canneal 840063.600 839145.200 (-0.11) 839506.200 (-0.07) 835102.600 (-0.59) 839766.000 (-0.04) 833091.800 (-0.83)
+ parsec3/dedup 1185493.200 1202688.800 (1.45) 1204597.000 (1.61) 1238071.400 (4.44) 1201689.400 (1.37) 920688.600 (-22.34)
+ parsec3/facesim 311570.400 311542.000 (-0.01) 311665.000 (0.03) 316106.400 (1.46) 312003.400 (0.14) 252646.000 (-18.91)
+ parsec3/ferret 99783.200 99330.000 (-0.45) 99735.000 (-0.05) 102000.600 (2.22) 99927.400 (0.14) 90967.400 (-8.83)
+ parsec3/fluidanimate 531780.800 531800.800 (0.00) 531754.600 (-0.00) 532009.600 (0.04) 531822.400 (0.01) 479116.000 (-9.90)
+ parsec3/freqmine 551787.600 551550.600 (-0.04) 551950.000 (0.03) 556030.000 (0.77) 553720.400 (0.35) 66480.000 (-87.95)
+ parsec3/raytrace 895247.000 895240.200 (-0.00) 895770.400 (0.06) 895880.200 (0.07) 893516.600 (-0.19) 327339.600 (-63.44)
+ parsec3/streamcluster 110862.200 110840.400 (-0.02) 110878.600 (0.01) 112067.200 (1.09) 112010.800 (1.04) 109763.600 (-0.99)
+ parsec3/swaptions 5630.000 5580.800 (-0.87) 5599.600 (-0.54) 5624.200 (-0.10) 5697.400 (1.20) 3792.400 (-32.64)
+ parsec3/vips 31677.200 31881.800 (0.65) 31785.800 (0.34) 32177.000 (1.58) 32456.800 (2.46) 29692.000 (-6.27)
+ parsec3/x264 81796.400 81918.600 (0.15) 81827.600 (0.04) 82734.800 (1.15) 82854.000 (1.29) 81478.200 (-0.39)
+ splash2x/barnes 1216014.600 1215462.000 (-0.05) 1218535.200 (0.21) 1227689.400 (0.96) 1219022.000 (0.25) 650771.000 (-46.48)
+ splash2x/fft 9622775.200 9511973.400 (-1.15) 9688178.600 (0.68) 9733868.400 (1.15) 9651488.000 (0.30) 7567077.400 (-21.36)
+ splash2x/lu_cb 511102.400 509911.600 (-0.23) 511123.800 (0.00) 514466.800 (0.66) 510462.800 (-0.13) 361014.000 (-29.37)
+ splash2x/lu_ncb 510569.800 510724.600 (0.03) 510888.800 (0.06) 513951.600 (0.66) 509474.400 (-0.21) 424030.400 (-16.95)
+ splash2x/ocean_cp 3413563.600 3413721.800 (0.00) 3398399.600 (-0.44) 3446878.000 (0.98) 3404799.200 (-0.26) 3244787.400 (-4.94)
+ splash2x/ocean_ncp 3927797.400 3936294.400 (0.22) 3917698.800 (-0.26) 7181781.200 (82.85) 4525783.600 (15.22) 3693747.800 (-5.96)
+ splash2x/radiosity 1477264.800 1477569.200 (0.02) 1476954.200 (-0.02) 1485724.800 (0.57) 1474684.800 (-0.17) 230128.000 (-84.42)
+ splash2x/radix 1773025.000 1754424.200 (-1.05) 1743194.400 (-1.68) 1445575.200 (-18.47) 1694855.200 (-4.41) 1769750.000 (-0.18)
+ splash2x/raytrace 23292.000 23284.000 (-0.03) 23292.800 (0.00) 28704.800 (23.24) 26489.600 (13.73) 15753.000 (-32.37)
+ splash2x/volrend 44095.800 44068.200 (-0.06) 44107.600 (0.03) 44114.600 (0.04) 44054.000 (-0.09) 31616.000 (-28.30)
+ splash2x/water_nsquared 29416.800 29403.200 (-0.05) 29406.400 (-0.04) 30103.200 (2.33) 29433.600 (0.06) 24927.400 (-15.26)
+ splash2x/water_spatial 657791.000 657840.400 (0.01) 657826.600 (0.01) 657595.800 (-0.03) 656617.800 (-0.18) 481334.800 (-26.83)
+ total 28475091.000 28368400.000 (-0.37) 28508700.000 (0.12) 31641800.000 (11.12) 29036000.000 (1.97) 21989800.000 (-22.78)
+
+In total, 22.78% of residential sets were reduced.
+
+With parsec3/freqmine, 'prcl' reduced 87.95% of residential sets and 29.52% of
+system memory usage while incurring only 2.15% runtime overhead.
diff --git a/Documentation/vm/damon/faq.rst b/Documentation/vm/damon/faq.rst
new file mode 100644
index 000000000000..088128bbf22b
--- /dev/null
+++ b/Documentation/vm/damon/faq.rst
@@ -0,0 +1,58 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+==========================
+Frequently Asked Questions
+==========================
+
+Why a new subsystem, instead of extending perf or other user space tools?
+=========================================================================
+
+First, because it needs to be lightweight as much as possible so that it can be
+used online, any unnecessary overhead such as kernel - user space context
+switching cost should be avoided. Second, DAMON aims to be used by other
+programs including the kernel. Therefore, having a dependency on specific
+tools like perf is not desirable. These are the two biggest reasons why DAMON
+is implemented in the kernel space.
+
+
+Can 'idle pages tracking' or 'perf mem' substitute DAMON?
+=========================================================
+
+Idle page tracking is a low level primitive for access check of the physical
+address space. 'perf mem' is similar, though it can use sampling to minimize
+the overhead. On the other hand, DAMON is a higher-level framework for the
+monitoring of various address spaces. It is focused on memory management
+optimization and provides sophisticated accuracy/overhead handling mechanisms.
+Therefore, 'idle pages tracking' and 'perf mem' could provide a subset of
+DAMON's output, but cannot substitute DAMON.
+
+
+How can I optimize my system's memory management using DAMON?
+=============================================================
+
+Because there are several ways for the DAMON-based optimizations, we wrote a
+separate document, :doc:`/admin-guide/mm/damon/guide`. Please refer to that.
+
+
+Does DAMON support virtual memory only?
+=======================================
+
+No. The core of the DAMON is address space independent. The address space
+specific low level primitive parts including monitoring target regions
+constructions and actual access checks can be implemented and configured on the
+DAMON core by the users. In this way, DAMON users can monitor any address
+space with any access check technique.
+
+Nonetheless, DAMON provides vma tracking and PTE Accessed bit check based
+implementations of the address space dependent functions for the virtual memory
+by default, for a reference and convenient use. In near future, we will
+provide those for physical memory address space.
+
+
+Can I simply monitor page granularity?
+======================================
+
+Yes. You can do so by setting the ``min_nr_regions`` attribute higher than the
+working set size divided by the page size. Because the monitoring target
+regions size is forced to be ``>=page size``, the region split will make no
+effect.
diff --git a/Documentation/vm/damon/index.rst b/Documentation/vm/damon/index.rst
new file mode 100644
index 000000000000..17dca3c12aad
--- /dev/null
+++ b/Documentation/vm/damon/index.rst
@@ -0,0 +1,31 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+==========================
+DAMON: Data Access MONitor
+==========================
+
+DAMON is a data access monitoring framework subsystem for the Linux kernel.
+The core mechanisms of DAMON (refer to :doc:`design` for the detail) make it
+
+ - *accurate* (the monitoring output is useful enough for DRAM level memory
+ management; It might not appropriate for CPU Cache levels, though),
+ - *light-weight* (the monitoring overhead is low enough to be applied online),
+ and
+ - *scalable* (the upper-bound of the overhead is in constant range regardless
+ of the size of target workloads).
+
+Using this framework, therefore, the kernel's memory management mechanisms can
+make advanced decisions. Experimental memory management optimization works
+that incurring high data accesses monitoring overhead could implemented again.
+In user space, meanwhile, users who have some special workloads can write
+personalized applications for better understanding and optimizations of their
+workloads and systems.
+
+.. toctree::
+ :maxdepth: 2
+
+ faq
+ design
+ eval
+ api
+ plans
diff --git a/Documentation/vm/index.rst b/Documentation/vm/index.rst
index 611140ffef7e..8d8d088bc7af 100644
--- a/Documentation/vm/index.rst
+++ b/Documentation/vm/index.rst
@@ -31,6 +31,7 @@ descriptions of data structures and algorithms.
active_mm
balance
cleancache
+ damon/index
free_page_reporting
frontswap
highmem
--
2.17.1
From: SeongJae Park <[email protected]>
This commit imtroduces a shallow wrapper python script,
``/tools/damon/damo`` that provides more convenient interface. Note
that it is only aimed to be used for minimal reference of the DAMON's
debugfs interfaces and for debugging of the DAMON itself.
Signed-off-by: SeongJae Park <[email protected]>
---
tools/damon/.gitignore | 1 +
tools/damon/_damon.py | 130 ++++++++++++++
tools/damon/_dist.py | 36 ++++
tools/damon/_recfile.py | 23 +++
tools/damon/bin2txt.py | 67 +++++++
tools/damon/damo | 37 ++++
tools/damon/heats.py | 362 ++++++++++++++++++++++++++++++++++++++
tools/damon/nr_regions.py | 91 ++++++++++
tools/damon/record.py | 135 ++++++++++++++
tools/damon/report.py | 45 +++++
tools/damon/wss.py | 100 +++++++++++
11 files changed, 1027 insertions(+)
create mode 100644 tools/damon/.gitignore
create mode 100644 tools/damon/_damon.py
create mode 100644 tools/damon/_dist.py
create mode 100644 tools/damon/_recfile.py
create mode 100644 tools/damon/bin2txt.py
create mode 100755 tools/damon/damo
create mode 100644 tools/damon/heats.py
create mode 100644 tools/damon/nr_regions.py
create mode 100644 tools/damon/record.py
create mode 100644 tools/damon/report.py
create mode 100644 tools/damon/wss.py
diff --git a/tools/damon/.gitignore b/tools/damon/.gitignore
new file mode 100644
index 000000000000..96403d36ff93
--- /dev/null
+++ b/tools/damon/.gitignore
@@ -0,0 +1 @@
+__pycache__/*
diff --git a/tools/damon/_damon.py b/tools/damon/_damon.py
new file mode 100644
index 000000000000..1f6a292e8c25
--- /dev/null
+++ b/tools/damon/_damon.py
@@ -0,0 +1,130 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+
+"""
+Contains core functions for DAMON debugfs control.
+"""
+
+import os
+import subprocess
+
+debugfs_attrs = None
+debugfs_record = None
+debugfs_target_ids = None
+debugfs_monitor_on = None
+
+def set_target_id(tid):
+ with open(debugfs_target_ids, 'w') as f:
+ f.write('%s\n' % tid)
+
+def turn_damon(on_off):
+ return subprocess.call("echo %s > %s" % (on_off, debugfs_monitor_on),
+ shell=True, executable="/bin/bash")
+
+def is_damon_running():
+ with open(debugfs_monitor_on, 'r') as f:
+ return f.read().strip() == 'on'
+
+class Attrs:
+ sample_interval = None
+ aggr_interval = None
+ regions_update_interval = None
+ min_nr_regions = None
+ max_nr_regions = None
+ rbuf_len = None
+ rfile_path = None
+
+ def __init__(self, s, a, r, n, x, l, f):
+ self.sample_interval = s
+ self.aggr_interval = a
+ self.regions_update_interval = r
+ self.min_nr_regions = n
+ self.max_nr_regions = x
+ self.rbuf_len = l
+ self.rfile_path = f
+
+ def __str__(self):
+ return "%s %s %s %s %s %s %s" % (self.sample_interval,
+ self.aggr_interval, self.regions_update_interval,
+ self.min_nr_regions, self.max_nr_regions, self.rbuf_len,
+ self.rfile_path)
+
+ def attr_str(self):
+ return "%s %s %s %s %s " % (self.sample_interval, self.aggr_interval,
+ self.regions_update_interval, self.min_nr_regions,
+ self.max_nr_regions)
+
+ def record_str(self):
+ return '%s %s ' % (self.rbuf_len, self.rfile_path)
+
+ def apply(self):
+ ret = subprocess.call('echo %s > %s' % (self.attr_str(), debugfs_attrs),
+ shell=True, executable='/bin/bash')
+ if ret:
+ return ret
+ ret = subprocess.call('echo %s > %s' % (self.record_str(),
+ debugfs_record), shell=True, executable='/bin/bash')
+ if ret:
+ return ret
+
+def current_attrs():
+ with open(debugfs_attrs, 'r') as f:
+ attrs = f.read().split()
+ attrs = [int(x) for x in attrs]
+
+ with open(debugfs_record, 'r') as f:
+ rattrs = f.read().split()
+ attrs.append(int(rattrs[0]))
+ attrs.append(rattrs[1])
+
+ return Attrs(*attrs)
+
+def chk_update_debugfs(debugfs):
+ global debugfs_attrs
+ global debugfs_record
+ global debugfs_target_ids
+ global debugfs_monitor_on
+
+ debugfs_damon = os.path.join(debugfs, 'damon')
+ debugfs_attrs = os.path.join(debugfs_damon, 'attrs')
+ debugfs_record = os.path.join(debugfs_damon, 'record')
+ debugfs_target_ids = os.path.join(debugfs_damon, 'target_ids')
+ debugfs_monitor_on = os.path.join(debugfs_damon, 'monitor_on')
+
+ if not os.path.isdir(debugfs_damon):
+ print("damon debugfs dir (%s) not found", debugfs_damon)
+ exit(1)
+
+ for f in [debugfs_attrs, debugfs_record, debugfs_target_ids,
+ debugfs_monitor_on]:
+ if not os.path.isfile(f):
+ print("damon debugfs file (%s) not found" % f)
+ exit(1)
+
+def cmd_args_to_attrs(args):
+ "Generate attributes with specified arguments"
+ sample_interval = args.sample
+ aggr_interval = args.aggr
+ regions_update_interval = args.updr
+ min_nr_regions = args.minr
+ max_nr_regions = args.maxr
+ rbuf_len = args.rbuf
+ if not os.path.isabs(args.out):
+ args.out = os.path.join(os.getcwd(), args.out)
+ rfile_path = args.out
+ return Attrs(sample_interval, aggr_interval, regions_update_interval,
+ min_nr_regions, max_nr_regions, rbuf_len, rfile_path)
+
+def set_attrs_argparser(parser):
+ parser.add_argument('-d', '--debugfs', metavar='<debugfs>', type=str,
+ default='/sys/kernel/debug', help='debugfs mounted path')
+ parser.add_argument('-s', '--sample', metavar='<interval>', type=int,
+ default=5000, help='sampling interval')
+ parser.add_argument('-a', '--aggr', metavar='<interval>', type=int,
+ default=100000, help='aggregate interval')
+ parser.add_argument('-u', '--updr', metavar='<interval>', type=int,
+ default=1000000, help='regions update interval')
+ parser.add_argument('-n', '--minr', metavar='<# regions>', type=int,
+ default=10, help='minimal number of regions')
+ parser.add_argument('-m', '--maxr', metavar='<# regions>', type=int,
+ default=1000, help='maximum number of regions')
diff --git a/tools/damon/_dist.py b/tools/damon/_dist.py
new file mode 100644
index 000000000000..9851ec964e5c
--- /dev/null
+++ b/tools/damon/_dist.py
@@ -0,0 +1,36 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+
+import os
+import struct
+import subprocess
+
+def access_patterns(f):
+ nr_regions = struct.unpack('I', f.read(4))[0]
+
+ patterns = []
+ for r in range(nr_regions):
+ saddr = struct.unpack('L', f.read(8))[0]
+ eaddr = struct.unpack('L', f.read(8))[0]
+ nr_accesses = struct.unpack('I', f.read(4))[0]
+ patterns.append([eaddr - saddr, nr_accesses])
+ return patterns
+
+def plot_dist(data_file, output_file, xlabel, ylabel):
+ terminal = output_file.split('.')[-1]
+ if not terminal in ['pdf', 'jpeg', 'png', 'svg']:
+ os.remove(data_file)
+ print("Unsupported plot output type.")
+ exit(-1)
+
+ gnuplot_cmd = """
+ set term %s;
+ set output '%s';
+ set key off;
+ set xlabel '%s';
+ set ylabel '%s';
+ plot '%s' with linespoints;""" % (terminal, output_file, xlabel, ylabel,
+ data_file)
+ subprocess.call(['gnuplot', '-e', gnuplot_cmd])
+ os.remove(data_file)
+
diff --git a/tools/damon/_recfile.py b/tools/damon/_recfile.py
new file mode 100644
index 000000000000..45dd8ffdb5ae
--- /dev/null
+++ b/tools/damon/_recfile.py
@@ -0,0 +1,23 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+
+import struct
+
+fmt_version = 0
+
+def set_fmt_version(f):
+ global fmt_version
+
+ mark = f.read(16)
+ if mark == b'damon_recfmt_ver':
+ fmt_version = struct.unpack('i', f.read(4))[0]
+ else:
+ fmt_version = 0
+ f.seek(0)
+ return fmt_version
+
+def target_id(f):
+ if fmt_version == 1:
+ return struct.unpack('i', f.read(4))[0]
+ else:
+ return struct.unpack('L', f.read(8))[0]
diff --git a/tools/damon/bin2txt.py b/tools/damon/bin2txt.py
new file mode 100644
index 000000000000..79516c72f449
--- /dev/null
+++ b/tools/damon/bin2txt.py
@@ -0,0 +1,67 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+
+import argparse
+import os
+import struct
+import sys
+
+import _recfile
+
+def parse_time(bindat):
+ "bindat should be 16 bytes"
+ sec = struct.unpack('l', bindat[0:8])[0]
+ nsec = struct.unpack('l', bindat[8:16])[0]
+ return sec * 1000000000 + nsec;
+
+def pr_region(f):
+ saddr = struct.unpack('L', f.read(8))[0]
+ eaddr = struct.unpack('L', f.read(8))[0]
+ nr_accesses = struct.unpack('I', f.read(4))[0]
+ print("%012x-%012x(%10d):\t%d" %
+ (saddr, eaddr, eaddr - saddr, nr_accesses))
+
+def pr_task_info(f):
+ target_id = _recfile.target_id(f)
+ print("target_id: ", target_id)
+ nr_regions = struct.unpack('I', f.read(4))[0]
+ print("nr_regions: ", nr_regions)
+ for r in range(nr_regions):
+ pr_region(f)
+
+def set_argparser(parser):
+ parser.add_argument('--input', '-i', type=str, metavar='<file>',
+ default='damon.data', help='input file name')
+
+def main(args=None):
+ if not args:
+ parser = argparse.ArgumentParser()
+ set_argparser(parser)
+ args = parser.parse_args()
+
+ file_path = args.input
+
+ if not os.path.isfile(file_path):
+ print('input file (%s) is not exist' % file_path)
+ exit(1)
+
+ with open(file_path, 'rb') as f:
+ _recfile.set_fmt_version(f)
+ start_time = None
+ while True:
+ timebin = f.read(16)
+ if len(timebin) != 16:
+ break
+ time = parse_time(timebin)
+ if not start_time:
+ start_time = time
+ print("start_time: ", start_time)
+ print("rel time: %16d" % (time - start_time))
+ nr_tasks = struct.unpack('I', f.read(4))[0]
+ print("nr_tasks: ", nr_tasks)
+ for t in range(nr_tasks):
+ pr_task_info(f)
+ print("")
+
+if __name__ == '__main__':
+ main()
diff --git a/tools/damon/damo b/tools/damon/damo
new file mode 100755
index 000000000000..58e1099ae5fc
--- /dev/null
+++ b/tools/damon/damo
@@ -0,0 +1,37 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+
+import argparse
+
+import record
+import report
+
+class SubCmdHelpFormatter(argparse.RawDescriptionHelpFormatter):
+ def _format_action(self, action):
+ parts = super(argparse.RawDescriptionHelpFormatter,
+ self)._format_action(action)
+ # skip sub parsers help
+ if action.nargs == argparse.PARSER:
+ parts = '\n'.join(parts.split('\n')[1:])
+ return parts
+
+parser = argparse.ArgumentParser(formatter_class=SubCmdHelpFormatter)
+
+subparser = parser.add_subparsers(title='command', dest='command',
+ metavar='<command>')
+subparser.required = True
+
+parser_record = subparser.add_parser('record',
+ help='record data accesses of the given target processes')
+record.set_argparser(parser_record)
+
+parser_report = subparser.add_parser('report',
+ help='report the recorded data accesses in the specified form')
+report.set_argparser(parser_report)
+
+args = parser.parse_args()
+
+if args.command == 'record':
+ record.main(args)
+elif args.command == 'report':
+ report.main(args)
diff --git a/tools/damon/heats.py b/tools/damon/heats.py
new file mode 100644
index 000000000000..78a2a793f50e
--- /dev/null
+++ b/tools/damon/heats.py
@@ -0,0 +1,362 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+
+"""
+Transform binary trace data into human readable text that can be used for
+heatmap drawing, or directly plot the data in a heatmap format.
+
+Format of the text is:
+
+ <time> <space> <heat>
+ ...
+
+"""
+
+import argparse
+import os
+import struct
+import subprocess
+import sys
+import tempfile
+
+import _recfile
+
+class HeatSample:
+ space_idx = None
+ sz_time_space = None
+ heat = None
+
+ def __init__(self, space_idx, sz_time_space, heat):
+ if sz_time_space < 0:
+ raise RuntimeError()
+ self.space_idx = space_idx
+ self.sz_time_space = sz_time_space
+ self.heat = heat
+
+ def total_heat(self):
+ return self.heat * self.sz_time_space
+
+ def merge(self, sample):
+ "sample must have a space idx that same to self"
+ heat_sum = self.total_heat() + sample.total_heat()
+ self.heat = heat_sum / (self.sz_time_space + sample.sz_time_space)
+ self.sz_time_space += sample.sz_time_space
+
+def pr_samples(samples, time_idx, time_unit, region_unit):
+ display_time = time_idx * time_unit
+ for idx, sample in enumerate(samples):
+ display_addr = idx * region_unit
+ if not sample:
+ print("%s\t%s\t%s" % (display_time, display_addr, 0.0))
+ continue
+ print("%s\t%s\t%s" % (display_time, display_addr, sample.total_heat() /
+ time_unit / region_unit))
+
+def to_idx(value, min_, unit):
+ return (value - min_) // unit
+
+def read_task_heats(f, tid, aunit, amin, amax):
+ tid_ = _recfile.target_id(f)
+ nr_regions = struct.unpack('I', f.read(4))[0]
+ if tid_ != tid:
+ f.read(20 * nr_regions)
+ return None
+ samples = []
+ for i in range(nr_regions):
+ saddr = struct.unpack('L', f.read(8))[0]
+ eaddr = struct.unpack('L', f.read(8))[0]
+ eaddr = min(eaddr, amax - 1)
+ heat = struct.unpack('I', f.read(4))[0]
+
+ if eaddr <= amin:
+ continue
+ if saddr >= amax:
+ continue
+ saddr = max(amin, saddr)
+ eaddr = min(amax, eaddr)
+
+ sidx = to_idx(saddr, amin, aunit)
+ eidx = to_idx(eaddr - 1, amin, aunit)
+ for idx in range(sidx, eidx + 1):
+ sa = max(amin + idx * aunit, saddr)
+ ea = min(amin + (idx + 1) * aunit, eaddr)
+ sample = HeatSample(idx, (ea - sa), heat)
+ samples.append(sample)
+ return samples
+
+def parse_time(bindat):
+ sec = struct.unpack('l', bindat[0:8])[0]
+ nsec = struct.unpack('l', bindat[8:16])[0]
+ return sec * 1000000000 + nsec
+
+def apply_samples(target_samples, samples, start_time, end_time, aunit, amin):
+ for s in samples:
+ sample = HeatSample(s.space_idx,
+ s.sz_time_space * (end_time - start_time), s.heat)
+ idx = sample.space_idx
+ if not target_samples[idx]:
+ target_samples[idx] = sample
+ else:
+ target_samples[idx].merge(sample)
+
+def __pr_heats(f, tid, tunit, tmin, tmax, aunit, amin, amax):
+ heat_samples = [None] * ((amax - amin) // aunit)
+
+ start_time = 0
+ end_time = 0
+ last_flushed = -1
+ while True:
+ start_time = end_time
+ timebin = f.read(16)
+ if (len(timebin)) != 16:
+ break
+ end_time = parse_time(timebin)
+ nr_tasks = struct.unpack('I', f.read(4))[0]
+ samples_set = {}
+ for t in range(nr_tasks):
+ samples = read_task_heats(f, tid, aunit, amin, amax)
+ if samples:
+ samples_set[tid] = samples
+ if not tid in samples_set:
+ continue
+ if start_time >= tmax:
+ continue
+ if end_time <= tmin:
+ continue
+ start_time = max(start_time, tmin)
+ end_time = min(end_time, tmax)
+
+ sidx = to_idx(start_time, tmin, tunit)
+ eidx = to_idx(end_time - 1, tmin, tunit)
+ for idx in range(sidx, eidx + 1):
+ if idx != last_flushed:
+ pr_samples(heat_samples, idx, tunit, aunit)
+ heat_samples = [None] * ((amax - amin) // aunit)
+ last_flushed = idx
+ st = max(start_time, tmin + idx * tunit)
+ et = min(end_time, tmin + (idx + 1) * tunit)
+ apply_samples(heat_samples, samples_set[tid], st, et, aunit, amin)
+
+def pr_heats(args):
+ binfile = args.input
+ tid = args.tid
+ tres = args.tres
+ tmin = args.tmin
+ ares = args.ares
+ amin = args.amin
+
+ tunit = (args.tmax - tmin) // tres
+ aunit = (args.amax - amin) // ares
+
+ # Compensate the values so that those fit with the resolution
+ tmax = tmin + tunit * tres
+ amax = amin + aunit * ares
+
+ with open(binfile, 'rb') as f:
+ _recfile.set_fmt_version(f)
+ __pr_heats(f, tid, tunit, tmin, tmax, aunit, amin, amax)
+
+class GuideInfo:
+ tid = None
+ start_time = None
+ end_time = None
+ lowest_addr = None
+ highest_addr = None
+ gaps = None
+
+ def __init__(self, tid, start_time):
+ self.tid = tid
+ self.start_time = start_time
+ self.gaps = []
+
+ def regions(self):
+ regions = []
+ region = [self.lowest_addr]
+ for gap in self.gaps:
+ for idx, point in enumerate(gap):
+ if idx == 0:
+ region.append(point)
+ regions.append(region)
+ else:
+ region = [point]
+ region.append(self.highest_addr)
+ regions.append(region)
+ return regions
+
+ def total_space(self):
+ ret = 0
+ for r in self.regions():
+ ret += r[1] - r[0]
+ return ret
+
+ def __str__(self):
+ lines = ['target_id:%d' % self.tid]
+ lines.append('time: %d-%d (%d)' % (self.start_time, self.end_time,
+ self.end_time - self.start_time))
+ for idx, region in enumerate(self.regions()):
+ lines.append('region\t%2d: %020d-%020d (%d)' %
+ (idx, region[0], region[1], region[1] - region[0]))
+ return '\n'.join(lines)
+
+def is_overlap(region1, region2):
+ if region1[1] < region2[0]:
+ return False
+ if region2[1] < region1[0]:
+ return False
+ return True
+
+def overlap_region_of(region1, region2):
+ return [max(region1[0], region2[0]), min(region1[1], region2[1])]
+
+def overlapping_regions(regions1, regions2):
+ overlap_regions = []
+ for r1 in regions1:
+ for r2 in regions2:
+ if is_overlap(r1, r2):
+ r1 = overlap_region_of(r1, r2)
+ if r1:
+ overlap_regions.append(r1)
+ return overlap_regions
+
+def get_guide_info(binfile):
+ "Read file, return the set of guide information objects of the data"
+ guides = {}
+ with open(binfile, 'rb') as f:
+ _recfile.set_fmt_version(f)
+ while True:
+ timebin = f.read(16)
+ if len(timebin) != 16:
+ break
+ monitor_time = parse_time(timebin)
+ nr_tasks = struct.unpack('I', f.read(4))[0]
+ for t in range(nr_tasks):
+ tid = _recfile.target_id(f)
+ nr_regions = struct.unpack('I', f.read(4))[0]
+ if not tid in guides:
+ guides[tid] = GuideInfo(tid, monitor_time)
+ guide = guides[tid]
+ guide.end_time = monitor_time
+
+ last_addr = None
+ gaps = []
+ for r in range(nr_regions):
+ saddr = struct.unpack('L', f.read(8))[0]
+ eaddr = struct.unpack('L', f.read(8))[0]
+ f.read(4)
+
+ if not guide.lowest_addr or saddr < guide.lowest_addr:
+ guide.lowest_addr = saddr
+ if not guide.highest_addr or eaddr > guide.highest_addr:
+ guide.highest_addr = eaddr
+
+ if not last_addr:
+ last_addr = eaddr
+ continue
+ if last_addr != saddr:
+ gaps.append([last_addr, saddr])
+ last_addr = eaddr
+
+ if not guide.gaps:
+ guide.gaps = gaps
+ else:
+ guide.gaps = overlapping_regions(guide.gaps, gaps)
+ return sorted(list(guides.values()), key=lambda x: x.total_space(),
+ reverse=True)
+
+def pr_guide(binfile):
+ for guide in get_guide_info(binfile):
+ print(guide)
+
+def region_sort_key(region):
+ return region[1] - region[0]
+
+def set_missed_args(args):
+ if args.tid and args.tmin and args.tmax and args.amin and args.amax:
+ return
+ guides = get_guide_info(args.input)
+ guide = guides[0]
+ if not args.tid:
+ args.tid = guide.tid
+ for g in guides:
+ if g.tid == args.tid:
+ guide = g
+ break
+
+ if not args.tmin:
+ args.tmin = guide.start_time
+ if not args.tmax:
+ args.tmax = guide.end_time
+
+ if not args.amin or not args.amax:
+ region = sorted(guide.regions(), key=lambda x: x[1] - x[0],
+ reverse=True)[0]
+ args.amin = region[0]
+ args.amax = region[1]
+
+def plot_heatmap(data_file, output_file):
+ terminal = output_file.split('.')[-1]
+ if not terminal in ['pdf', 'jpeg', 'png', 'svg']:
+ os.remove(data_file)
+ print("Unsupported plot output type.")
+ exit(-1)
+
+ gnuplot_cmd = """
+ set term %s;
+ set output '%s';
+ set key off;
+ set xrange [0:];
+ set yrange [0:];
+ set xlabel 'Time (ns)';
+ set ylabel 'Address (bytes)';
+ plot '%s' using 1:2:3 with image;""" % (terminal, output_file, data_file)
+ subprocess.call(['gnuplot', '-e', gnuplot_cmd])
+ os.remove(data_file)
+
+def set_argparser(parser):
+ parser.add_argument('--input', '-i', type=str, metavar='<file>',
+ default='damon.data', help='input file name')
+ parser.add_argument('--tid', metavar='<id>', type=int,
+ help='target id')
+ parser.add_argument('--tres', metavar='<resolution>', type=int,
+ default=500, help='time resolution of the output')
+ parser.add_argument('--tmin', metavar='<time>', type=lambda x: int(x,0),
+ help='minimal time of the output')
+ parser.add_argument('--tmax', metavar='<time>', type=lambda x: int(x,0),
+ help='maximum time of the output')
+ parser.add_argument('--ares', metavar='<resolution>', type=int, default=500,
+ help='space address resolution of the output')
+ parser.add_argument('--amin', metavar='<address>', type=lambda x: int(x,0),
+ help='minimal space address of the output')
+ parser.add_argument('--amax', metavar='<address>', type=lambda x: int(x,0),
+ help='maximum space address of the output')
+ parser.add_argument('--guide', action='store_true',
+ help='print a guidance for the min/max/resolution settings')
+ parser.add_argument('--heatmap', metavar='<file>', type=str,
+ help='heatmap image file to create')
+
+def main(args=None):
+ if not args:
+ parser = argparse.ArgumentParser()
+ set_argparser(parser)
+ args = parser.parse_args()
+
+ if args.guide:
+ pr_guide(args.input)
+ else:
+ set_missed_args(args)
+ orig_stdout = sys.stdout
+ if args.heatmap:
+ tmp_path = tempfile.mkstemp()[1]
+ tmp_file = open(tmp_path, 'w')
+ sys.stdout = tmp_file
+
+ pr_heats(args)
+
+ if args.heatmap:
+ sys.stdout = orig_stdout
+ tmp_file.flush()
+ tmp_file.close()
+ plot_heatmap(tmp_path, args.heatmap)
+
+if __name__ == '__main__':
+ main()
diff --git a/tools/damon/nr_regions.py b/tools/damon/nr_regions.py
new file mode 100644
index 000000000000..960dd4362472
--- /dev/null
+++ b/tools/damon/nr_regions.py
@@ -0,0 +1,91 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+
+"Print out distribution of the number of regions in the given record"
+
+import argparse
+import struct
+import sys
+import tempfile
+
+import _dist
+import _recfile
+
+def set_argparser(parser):
+ parser.add_argument('--input', '-i', type=str, metavar='<file>',
+ default='damon.data', help='input file name')
+ parser.add_argument('--range', '-r', type=int, nargs=3,
+ metavar=('<start>', '<stop>', '<step>'),
+ help='range of percentiles to print')
+ parser.add_argument('--sortby', '-s', choices=['time', 'size'],
+ help='the metric to be used for sorting the number of regions')
+ parser.add_argument('--plot', '-p', type=str, metavar='<file>',
+ help='plot the distribution to an image file')
+
+def main(args=None):
+ if not args:
+ parser = argparse.ArgumentParser()
+ set_argparser(parser)
+ args = parser.parse_args()
+
+ percentiles = [0, 25, 50, 75, 100]
+
+ file_path = args.input
+ if args.range:
+ percentiles = range(args.range[0], args.range[1], args.range[2])
+ nr_regions_sort = True
+ if args.sortby == 'time':
+ nr_regions_sort = False
+
+ tid_pattern_map = {}
+ with open(file_path, 'rb') as f:
+ _recfile.set_fmt_version(f)
+ start_time = None
+ while True:
+ timebin = f.read(16)
+ if len(timebin) != 16:
+ break
+ nr_tasks = struct.unpack('I', f.read(4))[0]
+ for t in range(nr_tasks):
+ tid = _recfile.target_id(f)
+ if not tid in tid_pattern_map:
+ tid_pattern_map[tid] = []
+ tid_pattern_map[tid].append(_dist.access_patterns(f))
+
+ orig_stdout = sys.stdout
+ if args.plot:
+ tmp_path = tempfile.mkstemp()[1]
+ tmp_file = open(tmp_path, 'w')
+ sys.stdout = tmp_file
+
+ print('# <percentile> <# regions>')
+ for tid in tid_pattern_map.keys():
+ # Skip firs 20 regions as those would not adaptively adjusted
+ snapshots = tid_pattern_map[tid][20:]
+ nr_regions_dist = []
+ for snapshot in snapshots:
+ nr_regions_dist.append(len(snapshot))
+ if nr_regions_sort:
+ nr_regions_dist.sort(reverse=False)
+
+ print('# target_id\t%s' % tid)
+ print('# avr:\t%d' % (sum(nr_regions_dist) / len(nr_regions_dist)))
+ for percentile in percentiles:
+ thres_idx = int(percentile / 100.0 * len(nr_regions_dist))
+ if thres_idx == len(nr_regions_dist):
+ thres_idx -= 1
+ threshold = nr_regions_dist[thres_idx]
+ print('%d\t%d' % (percentile, nr_regions_dist[thres_idx]))
+
+ if args.plot:
+ sys.stdout = orig_stdout
+ tmp_file.flush()
+ tmp_file.close()
+ xlabel = 'runtime (percent)'
+ if nr_regions_sort:
+ xlabel = 'percentile'
+ _dist.plot_dist(tmp_path, args.plot, xlabel,
+ 'number of monitoring target regions')
+
+if __name__ == '__main__':
+ main()
diff --git a/tools/damon/record.py b/tools/damon/record.py
new file mode 100644
index 000000000000..6d1cbe593b94
--- /dev/null
+++ b/tools/damon/record.py
@@ -0,0 +1,135 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+
+"""
+Record data access patterns of the target process.
+"""
+
+import argparse
+import os
+import signal
+import subprocess
+import time
+
+import _damon
+
+def pidfd_open(pid):
+ import ctypes
+ libc = ctypes.CDLL(None)
+ syscall = libc.syscall
+ syscall.argtypes = [ctypes.c_int, ctypes.c_int, ctypes.c_uint]
+ syscall.restype = ctypes.c_long
+
+ NR_pidfd_open = 434
+
+ return syscall(NR_pidfd_open, pid, 0)
+
+def do_record(target, is_target_cmd, attrs, old_attrs, pidfd):
+ if os.path.isfile(attrs.rfile_path):
+ os.rename(attrs.rfile_path, attrs.rfile_path + '.old')
+
+ if attrs.apply():
+ print('attributes (%s) failed to be applied' % attrs)
+ cleanup_exit(old_attrs, -1)
+ print('# damon attrs: %s %s' % (attrs.attr_str(), attrs.record_str()))
+ if is_target_cmd:
+ p = subprocess.Popen(target, shell=True, executable='/bin/bash')
+ target = p.pid
+
+ if pidfd:
+ fd = pidfd_open(int(target))
+ if fd < 0:
+ print('failed getting pidfd of %s: %s' % (target, fd))
+ cleanup_exit(old_attrs, -1)
+
+ # NOTE: The race is still possible because the pid might be already
+ # reused before above pidfd_open() returned. Eliminating the race is
+ # impossible unless we drop the pid support. This option handling is
+ # only for reference of the pidfd usage.
+ target = 'pidfd %s' % fd
+
+ if _damon.set_target_id(target):
+ print('target id setting (%s) failed' % target)
+ cleanup_exit(old_attrs, -2)
+ if _damon.turn_damon('on'):
+ print('could not turn on damon' % target)
+ cleanup_exit(old_attrs, -3)
+ while not _damon.is_damon_running():
+ time.sleep(1)
+ print('Press Ctrl+C to stop')
+ if is_target_cmd:
+ p.wait()
+ while True:
+ # damon will turn it off by itself if the target tasks are terminated.
+ if not _damon.is_damon_running():
+ break
+ time.sleep(1)
+
+ if pidfd:
+ os.close(fd)
+ cleanup_exit(old_attrs, 0)
+
+def cleanup_exit(orig_attrs, exit_code):
+ if _damon.is_damon_running():
+ if _damon.turn_damon('off'):
+ print('failed to turn damon off!')
+ while _damon.is_damon_running():
+ time.sleep(1)
+ if orig_attrs:
+ if orig_attrs.apply():
+ print('original attributes (%s) restoration failed!' % orig_attrs)
+ exit(exit_code)
+
+def sighandler(signum, frame):
+ print('\nsignal %s received' % signum)
+ cleanup_exit(orig_attrs, signum)
+
+def chk_permission():
+ if os.geteuid() != 0:
+ print("Run as root")
+ exit(1)
+
+def set_argparser(parser):
+ _damon.set_attrs_argparser(parser)
+ parser.add_argument('target', type=str, metavar='<target>',
+ help='the target command or the pid to record')
+ parser.add_argument('--pidfd', action='store_true',
+ help='use pidfd type target id')
+ parser.add_argument('-l', '--rbuf', metavar='<len>', type=int,
+ default=1024*1024, help='length of record result buffer')
+ parser.add_argument('-o', '--out', metavar='<file path>', type=str,
+ default='damon.data', help='output file path')
+
+def main(args=None):
+ global orig_attrs
+ if not args:
+ parser = argparse.ArgumentParser()
+ set_argparser(parser)
+ args = parser.parse_args()
+
+ chk_permission()
+ _damon.chk_update_debugfs(args.debugfs)
+
+ signal.signal(signal.SIGINT, sighandler)
+ signal.signal(signal.SIGTERM, sighandler)
+ orig_attrs = _damon.current_attrs()
+
+ args.schemes = ''
+ pidfd = args.pidfd
+ new_attrs = _damon.cmd_args_to_attrs(args)
+ target = args.target
+
+ target_fields = target.split()
+ if not subprocess.call('which %s &> /dev/null' % target_fields[0],
+ shell=True, executable='/bin/bash'):
+ do_record(target, True, new_attrs, orig_attrs, pidfd)
+ else:
+ try:
+ pid = int(target)
+ except:
+ print('target \'%s\' is neither a command, nor a pid' % target)
+ exit(1)
+ do_record(target, False, new_attrs, orig_attrs, pidfd)
+
+if __name__ == '__main__':
+ main()
diff --git a/tools/damon/report.py b/tools/damon/report.py
new file mode 100644
index 000000000000..c661c7b2f1af
--- /dev/null
+++ b/tools/damon/report.py
@@ -0,0 +1,45 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+
+import argparse
+
+import bin2txt
+import heats
+import nr_regions
+import wss
+
+def set_argparser(parser):
+ subparsers = parser.add_subparsers(title='report type', dest='report_type',
+ metavar='<report type>', help='the type of the report to generate')
+ subparsers.required = True
+
+ parser_raw = subparsers.add_parser('raw', help='human readable raw data')
+ bin2txt.set_argparser(parser_raw)
+
+ parser_heats = subparsers.add_parser('heats', help='heats of regions')
+ heats.set_argparser(parser_heats)
+
+ parser_wss = subparsers.add_parser('wss', help='working set size')
+ wss.set_argparser(parser_wss)
+
+ parser_nr_regions = subparsers.add_parser('nr_regions',
+ help='number of regions')
+ nr_regions.set_argparser(parser_nr_regions)
+
+def main(args=None):
+ if not args:
+ parser = argparse.ArgumentParser()
+ set_argparser(parser)
+ args = parser.parse_args()
+
+ if args.report_type == 'raw':
+ bin2txt.main(args)
+ elif args.report_type == 'heats':
+ heats.main(args)
+ elif args.report_type == 'wss':
+ wss.main(args)
+ elif args.report_type == 'nr_regions':
+ nr_regions.main(args)
+
+if __name__ == '__main__':
+ main()
diff --git a/tools/damon/wss.py b/tools/damon/wss.py
new file mode 100644
index 000000000000..54e2ac7cf83b
--- /dev/null
+++ b/tools/damon/wss.py
@@ -0,0 +1,100 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+
+"Print out the distribution of the working set sizes of the given trace"
+
+import argparse
+import struct
+import sys
+import tempfile
+
+import _dist
+import _recfile
+
+def set_argparser(parser):
+ parser.add_argument('--input', '-i', type=str, metavar='<file>',
+ default='damon.data', help='input file name')
+ parser.add_argument('--range', '-r', type=int, nargs=3,
+ metavar=('<start>', '<stop>', '<step>'),
+ help='range of wss percentiles to print')
+ parser.add_argument('--thres', '-t', type=int, default=1,
+ metavar='<# accesses>',
+ help='minimal number of accesses for treated as working set')
+ parser.add_argument('--sortby', '-s', choices=['time', 'size'],
+ help='the metric to be used for the sort of the working set sizes')
+ parser.add_argument('--plot', '-p', type=str, metavar='<file>',
+ help='plot the distribution to an image file')
+
+def main(args=None):
+ if not args:
+ parser = argparse.ArgumentParser()
+ set_argparser(parser)
+ args = parser.parse_args()
+
+ percentiles = [0, 25, 50, 75, 100]
+
+ file_path = args.input
+ if args.range:
+ percentiles = range(args.range[0], args.range[1], args.range[2])
+ wss_sort = True
+ if args.sortby == 'time':
+ wss_sort = False
+
+ tid_pattern_map = {}
+ with open(file_path, 'rb') as f:
+ _recfile.set_fmt_version(f)
+ start_time = None
+ while True:
+ timebin = f.read(16)
+ if len(timebin) != 16:
+ break
+ nr_tasks = struct.unpack('I', f.read(4))[0]
+ for t in range(nr_tasks):
+ tid = _recfile.target_id(f)
+ if not tid in tid_pattern_map:
+ tid_pattern_map[tid] = []
+ tid_pattern_map[tid].append(_dist.access_patterns(f))
+
+ orig_stdout = sys.stdout
+ if args.plot:
+ tmp_path = tempfile.mkstemp()[1]
+ tmp_file = open(tmp_path, 'w')
+ sys.stdout = tmp_file
+
+ print('# <percentile> <wss>')
+ for tid in tid_pattern_map.keys():
+ # Skip first 20 snapshots as regions may not adjusted yet.
+ snapshots = tid_pattern_map[tid][20:]
+ wss_dist = []
+ for snapshot in snapshots:
+ wss = 0
+ for p in snapshot:
+ # Ignore regions not accessed
+ if p[1] < args.thres:
+ continue
+ wss += p[0]
+ wss_dist.append(wss)
+ if wss_sort:
+ wss_dist.sort(reverse=False)
+
+ print('# target_id\t%s' % tid)
+ print('# avr:\t%d' % (sum(wss_dist) / len(wss_dist)))
+ for percentile in percentiles:
+ thres_idx = int(percentile / 100.0 * len(wss_dist))
+ if thres_idx == len(wss_dist):
+ thres_idx -= 1
+ threshold = wss_dist[thres_idx]
+ print('%d\t%d' % (percentile, wss_dist[thres_idx]))
+
+ if args.plot:
+ sys.stdout = orig_stdout
+ tmp_file.flush()
+ tmp_file.close()
+ xlabel = 'runtime (percent)'
+ if wss_sort:
+ xlabel = 'percentile'
+ _dist.plot_dist(tmp_path, args.plot, xlabel,
+ 'working set size (bytes)')
+
+if __name__ == '__main__':
+ main()
--
2.17.1
From: SeongJae Park <[email protected]>
This commit updates MAINTAINERS file for DAMON related files.
Signed-off-by: SeongJae Park <[email protected]>
---
MAINTAINERS | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/MAINTAINERS b/MAINTAINERS
index 4e2698cc7e23..3d6050d693e3 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4751,6 +4751,19 @@ F: net/ax25/ax25_out.c
F: net/ax25/ax25_timer.c
F: net/ax25/sysctl_net_ax25.c
+DATA ACCESS MONITOR
+M: SeongJae Park <[email protected]>
+L: [email protected]
+S: Maintained
+F: Documentation/admin-guide/mm/damon/*
+F: Documentation/vm/damon/*
+F: include/linux/damon.h
+F: include/trace/events/damon.h
+F: mm/damon-test.h
+F: mm/damon.c
+F: tools/damon/*
+F: tools/testing/selftests/damon/*
+
DAVICOM FAST ETHERNET (DMFE) NETWORK DRIVER
L: [email protected]
S: Orphan
--
2.17.1
From: SeongJae Park <[email protected]>
This commit adds a simple user space tests for DAMON. The tests are
using kselftest framework.
Signed-off-by: SeongJae Park <[email protected]>
---
tools/testing/selftests/damon/Makefile | 7 +
.../selftests/damon/_chk_dependency.sh | 28 +++
tools/testing/selftests/damon/_chk_record.py | 109 ++++++++++++
.../testing/selftests/damon/debugfs_attrs.sh | 161 ++++++++++++++++++
.../testing/selftests/damon/debugfs_record.sh | 50 ++++++
5 files changed, 355 insertions(+)
create mode 100644 tools/testing/selftests/damon/Makefile
create mode 100644 tools/testing/selftests/damon/_chk_dependency.sh
create mode 100644 tools/testing/selftests/damon/_chk_record.py
create mode 100755 tools/testing/selftests/damon/debugfs_attrs.sh
create mode 100755 tools/testing/selftests/damon/debugfs_record.sh
diff --git a/tools/testing/selftests/damon/Makefile b/tools/testing/selftests/damon/Makefile
new file mode 100644
index 000000000000..cfd5393a4639
--- /dev/null
+++ b/tools/testing/selftests/damon/Makefile
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0
+# Makefile for damon selftests
+
+TEST_FILES = _chk_dependency.sh _chk_record_file.py
+TEST_PROGS = debugfs_attrs.sh debugfs_record.sh
+
+include ../lib.mk
diff --git a/tools/testing/selftests/damon/_chk_dependency.sh b/tools/testing/selftests/damon/_chk_dependency.sh
new file mode 100644
index 000000000000..b304b7779976
--- /dev/null
+++ b/tools/testing/selftests/damon/_chk_dependency.sh
@@ -0,0 +1,28 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+# Kselftest framework requirement - SKIP code is 4.
+ksft_skip=4
+
+DBGFS=/sys/kernel/debug/damon
+
+if [ $EUID -ne 0 ];
+then
+ echo "Run as root"
+ exit $ksft_skip
+fi
+
+if [ ! -d $DBGFS ]
+then
+ echo "$DBGFS not found"
+ exit $ksft_skip
+fi
+
+for f in attrs record target_ids monitor_on
+do
+ if [ ! -f "$DBGFS/$f" ]
+ then
+ echo "$f not found"
+ exit 1
+ fi
+done
diff --git a/tools/testing/selftests/damon/_chk_record.py b/tools/testing/selftests/damon/_chk_record.py
new file mode 100644
index 000000000000..73e128904319
--- /dev/null
+++ b/tools/testing/selftests/damon/_chk_record.py
@@ -0,0 +1,109 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+
+"Check whether the DAMON record file is valid"
+
+import argparse
+import struct
+import sys
+
+fmt_version = 0
+
+def set_fmt_version(f):
+ global fmt_version
+
+ mark = f.read(16)
+ if mark == b'damon_recfmt_ver':
+ fmt_version = struct.unpack('i', f.read(4))[0]
+ else:
+ fmt_version = 0
+ f.seek(0)
+ return fmt_version
+
+def read_pid(f):
+ if fmt_version == 1:
+ pid = struct.unpack('i', f.read(4))[0]
+ else:
+ pid = struct.unpack('L', f.read(8))[0]
+
+def err_percent(val, expected):
+ return abs(val - expected) / expected * 100
+
+def chk_task_info(f):
+ pid = read_pid(f)
+ nr_regions = struct.unpack('I', f.read(4))[0]
+
+ if nr_regions > max_nr_regions:
+ print('too many regions: %d > %d' % (nr_regions, max_nr_regions))
+ exit(1)
+
+ nr_gaps = 0
+ eaddr = 0
+ for r in range(nr_regions):
+ saddr = struct.unpack('L', f.read(8))[0]
+ if eaddr and saddr != eaddr:
+ nr_gaps += 1
+ eaddr = struct.unpack('L', f.read(8))[0]
+ nr_accesses = struct.unpack('I', f.read(4))[0]
+
+ if saddr >= eaddr:
+ print('wrong region [%d,%d)' % (saddr, eaddr))
+ exit(1)
+
+ max_nr_accesses = aint / sint
+ if nr_accesses > max_nr_accesses:
+ if err_percent(nr_accesses, max_nr_accesses) > 15:
+ print('too high nr_access: expected %d but %d' %
+ (max_nr_accesses, nr_accesses))
+ exit(1)
+ if nr_gaps != 2:
+ print('number of gaps are not two but %d' % nr_gaps)
+ exit(1)
+
+def parse_time_us(bindat):
+ sec = struct.unpack('l', bindat[0:8])[0]
+ nsec = struct.unpack('l', bindat[8:16])[0]
+ return (sec * 1000000000 + nsec) / 1000
+
+def main():
+ global sint
+ global aint
+ global min_nr
+ global max_nr_regions
+
+ parser = argparse.ArgumentParser()
+ parser.add_argument('file', metavar='<file>',
+ help='path to the record file')
+ parser.add_argument('--attrs', metavar='<attrs>',
+ default='5000 100000 1000000 10 1000',
+ help='content of debugfs attrs file')
+ args = parser.parse_args()
+ file_path = args.file
+ attrs = [int(x) for x in args.attrs.split()]
+ sint, aint, rint, min_nr, max_nr_regions = attrs
+
+ with open(file_path, 'rb') as f:
+ set_fmt_version(f)
+ last_aggr_time = None
+ while True:
+ timebin = f.read(16)
+ if len(timebin) != 16:
+ break
+
+ now = parse_time_us(timebin)
+ if not last_aggr_time:
+ last_aggr_time = now
+ else:
+ error = err_percent(now - last_aggr_time, aint)
+ if error > 15:
+ print('wrong aggr interval: expected %d, but %d' %
+ (aint, now - last_aggr_time))
+ exit(1)
+ last_aggr_time = now
+
+ nr_tasks = struct.unpack('I', f.read(4))[0]
+ for t in range(nr_tasks):
+ chk_task_info(f)
+
+if __name__ == '__main__':
+ main()
diff --git a/tools/testing/selftests/damon/debugfs_attrs.sh b/tools/testing/selftests/damon/debugfs_attrs.sh
new file mode 100755
index 000000000000..c75557e8ba58
--- /dev/null
+++ b/tools/testing/selftests/damon/debugfs_attrs.sh
@@ -0,0 +1,161 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+source ./_chk_dependency.sh
+
+# Test attrs file
+file="$DBGFS/attrs"
+
+ORIG_CONTENT=$(cat $file)
+
+echo 1 2 3 4 5 > $file
+if [ $? -ne 0 ]
+then
+ echo "$file write failed"
+ echo $ORIG_CONTENT > $file
+ exit 1
+fi
+
+echo 1 2 3 4 > $file
+if [ $? -eq 0 ]
+then
+ echo "$file write success (should failed)"
+ echo $ORIG_CONTENT > $file
+ exit 1
+fi
+
+CONTENT=$(cat $file)
+if [ "$CONTENT" != "1 2 3 4 5" ]
+then
+ echo "$file not written"
+ echo $ORIG_CONTENT > $file
+ exit 1
+fi
+
+echo $ORIG_CONTENT > $file
+
+# Test record file
+file="$DBGFS/record"
+
+ORIG_CONTENT=$(cat $file)
+
+echo "4242 foo.bar" > $file
+if [ $? -ne 0 ]
+then
+ echo "$file writing sane input failed"
+ echo $ORIG_CONTENT > $file
+ exit 1
+fi
+
+echo abc 2 3 > $file
+if [ $? -eq 0 ]
+then
+ echo "$file writing insane input 1 success (should failed)"
+ echo $ORIG_CONTENT > $file
+ exit 1
+fi
+
+echo 123 > $file
+if [ $? -eq 0 ]
+then
+ echo "$file writing insane input 2 success (should failed)"
+ echo $ORIG_CONTENT > $file
+ exit 1
+fi
+
+CONTENT=$(cat $file)
+if [ "$CONTENT" != "4242 foo.bar" ]
+then
+ echo "$file not written"
+ echo $ORIG_CONTENT > $file
+ exit 1
+fi
+
+echo "0 null" > $file
+if [ $? -ne 0 ]
+then
+ echo "$file disabling write fail"
+ echo $ORIG_CONTENT > $file
+ exit 1
+fi
+
+CONTENT=$(cat $file)
+if [ "$CONTENT" != "0 null" ]
+then
+ echo "$file not disabled"
+ echo $ORIG_CONTENT > $file
+ exit 1
+fi
+
+echo "4242 foo.bar" > $file
+if [ $? -ne 0 ]
+then
+ echo "$file writing sane data again fail"
+ echo $ORIG_CONTENT > $file
+ exit 1
+fi
+
+echo $ORIG_CONTENT > $file
+
+# Test target_ids file
+file="$DBGFS/target_ids"
+
+ORIG_CONTENT=$(cat $file)
+
+echo "1 2 3 4" > $file
+if [ $? -ne 0 ]
+then
+ echo "$file write fail"
+ echo $ORIG_CONTENT > $file
+ exit 1
+fi
+
+echo "1 2 abc 4" > $file
+if [ $? -ne 0 ]
+then
+ echo "$file write fail"
+ echo $ORIG_CONTENT > $file
+ exit 1
+fi
+
+CONTENT=$(cat $file)
+if [ "$CONTENT" != "1 2" ]
+then
+ echo "$file not written"
+ echo $ORIG_CONTENT > $file
+ exit 1
+fi
+
+echo abc 2 3 > $file
+if [ $? -ne 0 ]
+then
+ echo "$file wrong value write fail"
+ echo $ORIG_CONTENT > $file
+ exit 1
+fi
+
+if [ ! -z "$(cat $file)" ]
+then
+ echo "$file not cleared"
+ echo $ORIG_CONTENT > $file
+ exit 1
+fi
+
+echo > $file
+if [ $? -ne 0 ]
+then
+ echo "$file init fail"
+ echo $ORIG_CONTENT > $file
+ exit 1
+fi
+
+if [ ! -z "$(cat $file)" ]
+then
+ echo "$file not initialized"
+ echo $ORIG_CONTENT > $file
+ exit 1
+fi
+
+echo $ORIG_CONTENT > $file
+
+echo "PASS"
diff --git a/tools/testing/selftests/damon/debugfs_record.sh b/tools/testing/selftests/damon/debugfs_record.sh
new file mode 100755
index 000000000000..c0fb8d24dc32
--- /dev/null
+++ b/tools/testing/selftests/damon/debugfs_record.sh
@@ -0,0 +1,50 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+source ./_chk_dependency.sh
+
+restore_attrs()
+{
+ echo $ORIG_ATTRS > $DBGFS/attrs
+ echo $ORIG_TARGET_IDS > $DBGFS/target_ids
+ echo $ORIG_RECORD > $DBGFS/record
+}
+
+ORIG_ATTRS=$(cat $DBGFS/attrs)
+ORIG_TARGET_IDS=$(cat $DBGFS/target_ids)
+ORIG_RECORD=$(cat $DBGFS/record)
+
+rfile=$pwd/damon.data
+
+rm -f $rfile
+ATTRS="5000 100000 1000000 10 1000"
+echo $ATTRS > $DBGFS/attrs
+echo 4096 $rfile > $DBGFS/record
+sleep 5 &
+echo $(pidof sleep) > $DBGFS/target_ids
+echo on > $DBGFS/monitor_on
+sleep 0.5
+killall sleep
+echo off > $DBGFS/monitor_on
+
+sync
+
+if [ ! -f $rfile ]
+then
+ echo "record file not made"
+ restore_attrs
+
+ exit 1
+fi
+
+python3 ./_chk_record.py $rfile --attrs "$ATTRS"
+if [ $? -ne 0 ]
+then
+ echo "record file is wrong"
+ restore_attrs
+ exit 1
+fi
+
+rm -f $rfile
+restore_attrs
+echo "PASS"
--
2.17.1
On Tue, 4 Aug 2020 11:14:09 +0200
SeongJae Park <[email protected]> wrote:
> From: SeongJae Park <[email protected]>
>
> This commit adds a tracepoint for DAMON. It traces the monitoring
> results of each region for each aggregation interval. Using this, DAMON
> can easily integrated with tracepoints supporting tools such as perf.
>
> Signed-off-by: SeongJae Park <[email protected]>
> Reviewed-by: Leonard Foerster <[email protected]>
> ---
> include/trace/events/damon.h | 43 ++++++++++++++++++++++++++++++++++++
> mm/damon.c | 4 ++++
> 2 files changed, 47 insertions(+)
> create mode 100644 include/trace/events/damon.h
>
> diff --git a/include/trace/events/damon.h b/include/trace/events/damon.h
> new file mode 100644
> index 000000000000..2f422f4f1fb9
> --- /dev/null
> +++ b/include/trace/events/damon.h
> @@ -0,0 +1,43 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#undef TRACE_SYSTEM
> +#define TRACE_SYSTEM damon
> +
> +#if !defined(_TRACE_DAMON_H) || defined(TRACE_HEADER_MULTI_READ)
> +#define _TRACE_DAMON_H
> +
> +#include <linux/damon.h>
> +#include <linux/types.h>
> +#include <linux/tracepoint.h>
> +
> +TRACE_EVENT(damon_aggregated,
> +
> + TP_PROTO(struct damon_target *t, struct damon_region *r,
> + unsigned int nr_regions),
> +
> + TP_ARGS(t, r, nr_regions),
> +
> + TP_STRUCT__entry(
> + __field(unsigned long, target_id)
> + __field(unsigned int, nr_regions)
> + __field(unsigned long, start)
> + __field(unsigned long, end)
> + __field(unsigned int, nr_accesses)
> + ),
> +
> + TP_fast_assign(
> + __entry->target_id = t->id;
> + __entry->nr_regions = nr_regions;
> + __entry->start = r->ar.start;
> + __entry->end = r->ar.end;
> + __entry->nr_accesses = r->nr_accesses;
> + ),
> +
> + TP_printk("target_id=%lu nr_regions=%u %lu-%lu: %u",
> + __entry->target_id, __entry->nr_regions,
> + __entry->start, __entry->end, __entry->nr_accesses)
> +);
> +
> +#endif /* _TRACE_DAMON_H */
> +
> +/* This part must be outside protection */
> +#include <trace/define_trace.h>
> diff --git a/mm/damon.c b/mm/damon.c
> index b3420ba97fd2..65e65e779313 100644
> --- a/mm/damon.c
> +++ b/mm/damon.c
> @@ -20,6 +20,8 @@
>
> #define pr_fmt(fmt) "damon: " fmt
>
> +#define CREATE_TRACE_POINTS
> +
> #include <linux/damon.h>
> #include <linux/delay.h>
> #include <linux/kthread.h>
> @@ -31,6 +33,7 @@
> #include <linux/sched/mm.h>
> #include <linux/sched/task.h>
> #include <linux/slab.h>
It's best to place the #define CREATE_TRACE_POINTS here, so that it
doesn't cause any side effects when including the other headers.
Other than that:
Reviewed-by: Steven Rostedt (VMware) <[email protected]>
-- Steve
> +#include <trace/events/damon.h>
>
> /* Minimal region size. Every damon_region is aligned by this. */
> #define MIN_REGION PAGE_SIZE
> @@ -856,6 +859,7 @@ static void kdamond_reset_aggregated(struct damon_ctx *c)
> damon_write_rbuf(c, &r->ar.end, sizeof(r->ar.end));
> damon_write_rbuf(c, &r->nr_accesses,
> sizeof(r->nr_accesses));
> + trace_damon_aggregated(t, r, nr);
> r->nr_accesses = 0;
> }
> }
On Tue, 4 Aug 2020 18:01:47 -0400 Steven Rostedt <[email protected]> wrote:
> On Tue, 4 Aug 2020 11:14:09 +0200
> SeongJae Park <[email protected]> wrote:
>
> > From: SeongJae Park <[email protected]>
> >
> > This commit adds a tracepoint for DAMON. It traces the monitoring
> > results of each region for each aggregation interval. Using this, DAMON
> > can easily integrated with tracepoints supporting tools such as perf.
> >
> > Signed-off-by: SeongJae Park <[email protected]>
> > Reviewed-by: Leonard Foerster <[email protected]>
> > ---
> > include/trace/events/damon.h | 43 ++++++++++++++++++++++++++++++++++++
> > mm/damon.c | 4 ++++
> > 2 files changed, 47 insertions(+)
> > create mode 100644 include/trace/events/damon.h
> >
[...]
> > --- a/mm/damon.c
> > +++ b/mm/damon.c
> > @@ -20,6 +20,8 @@
> >
> > #define pr_fmt(fmt) "damon: " fmt
> >
> > +#define CREATE_TRACE_POINTS
> > +
> > #include <linux/damon.h>
> > #include <linux/delay.h>
> > #include <linux/kthread.h>
> > @@ -31,6 +33,7 @@
> > #include <linux/sched/mm.h>
> > #include <linux/sched/task.h>
> > #include <linux/slab.h>
>
> It's best to place the #define CREATE_TRACE_POINTS here, so that it
> doesn't cause any side effects when including the other headers.
Agreed, I will do so in the next spin!
>
> Other than that:
>
> Reviewed-by: Steven Rostedt (VMware) <[email protected]>
>
> -- Steve
Thanks,
SeongJae Park
On Tue, 4 Aug 2020 11:14:10 +0200 SeongJae Park <[email protected]> wrote:
> From: SeongJae Park <[email protected]>
>
> This commit implements a debugfs interface for DAMON. It works for the
> virtual address spaces monitoring.
[...]
> +
> +#define targetid_is_pid(ctx) \
> + (ctx->target_valid == kdamond_vm_target_valid)
> +
[...]
> +
> +static ssize_t debugfs_target_ids_write(struct file *file,
> + const char __user *buf, size_t count, loff_t *ppos)
> +{
> + struct damon_ctx *ctx = &damon_user_ctx;
> + char *kbuf;
> + unsigned long *targets;
> + ssize_t nr_targets;
> + ssize_t ret = count;
> + struct damon_target *target;
> + int i;
> + int err;
> +
> + kbuf = user_input_str(buf, count, ppos);
> + if (IS_ERR(kbuf))
> + return PTR_ERR(kbuf);
> +
> + targets = str_to_target_ids(kbuf, ret, &nr_targets);
> + if (!targets) {
> + ret = -ENOMEM;
> + goto out;
> + }
> +
> + if (targetid_is_pid(ctx)) {
> + for (i = 0; i < nr_targets; i++)
> + targets[i] = (unsigned long)find_get_pid(
> + (int)targets[i]);
> + }
> +
> + mutex_lock(&ctx->kdamond_lock);
> + if (ctx->kdamond) {
> + ret = -EINVAL;
> + goto unlock_out;
> + }
> +
> + if (targetid_is_pid(ctx)) {
> + damon_for_each_target(target, ctx)
> + put_pid((struct pid *)target->id);
If non-pid target ids were set before by the kernel API, this will cause a
problem. Therefore, the DAMON users should cleanup there target ids properly.
However, I found that this could be easily missed. Indeed, my new test code
missed the cleanup. Moreover, it would be hard to do that when concurrent
DAMON users exist.
One straightforward fix would be making 'damon_set_targets()' to remember last
target id type and do 'put_pid()' if the last target id type was pid, instead
of here. This will work, but make the address space independent part to be
coupled with the dependent part.
Or, we could add another callback for cleanup and let debugfs code to register
a function doing 'put_pid()' and remove of the targets as the callback. This
approach will allow the address space independent part to be remain
independent.
I will fix this problem with the second approach in the next spin.
Thanks,
SeongJae Park
On Tue, 4 Aug 2020 11:14:03 +0200 SeongJae Park <[email protected]> wrote:
> From: SeongJae Park <[email protected]>
>
> DAMON separates its monitoring target address space independent high
> level logics from the target space dependent low level primitives for
> flexible support of various address spaces.
>
> This commit implements DAMON's target address space independent high
> level logics for basic access check and region based sampling. Hence,
> without the target address space specific parts implementations, this
> doesn't work alone. A reference implementation of those will be
> provided by a later commit.
[...]
> Signed-off-by: SeongJae Park <[email protected]>
> Reviewed-by: Leonard Foerster <[email protected]>
> ---
> include/linux/damon.h | 89 ++++++++++++++-
> mm/damon.c | 256 +++++++++++++++++++++++++++++++++++++++++-
> 2 files changed, 342 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/damon.h b/include/linux/damon.h
> index a6e839a236f4..0b1153971e6d 100644
> --- a/include/linux/damon.h
> +++ b/include/linux/damon.h
> @@ -11,6 +11,8 @@
> #define _DAMON_H_
>
> #include <linux/random.h>
> +#include <linux/mutex.h>
> +#include <linux/time64.h>
> #include <linux/types.h>
>
> /**
> @@ -56,11 +58,96 @@ struct damon_target {
> };
>
> /**
> - * struct damon_ctx - Represents a context for each monitoring.
> + * struct damon_ctx - Represents a context for each monitoring. This is the
> + * main interface that allows users to set the attributes and get the results
> + * of the monitoring.
> + *
> + * @sample_interval: The time between access samplings.
> + * @aggr_interval: The time between monitor results aggregations.
> + * @nr_regions: The number of monitoring regions.
> + *
> + * For each @sample_interval, DAMON checks whether each region is accessed or
> + * not. It aggregates and keeps the access information (number of accesses to
> + * each region) for @aggr_interval time. All time intervals are in
> + * micro-seconds.
> + *
> + * @kdamond: Kernel thread who does the monitoring.
> + * @kdamond_stop: Notifies whether kdamond should stop.
> + * @kdamond_lock: Mutex for the synchronizations with @kdamond.
> + *
> + * For each monitoring request (damon_start()), a kernel thread for the
> + * monitoring is created. The pointer to the thread is stored in @kdamond.
This means that multiple monitoring threads can concurrently run. This is an
intended design to let users utilize multiple CPUs. For example, let's suppose
the user need super high accuracy of the monitoring results which require
multiple CPU power. If use of the multiple CPUs are allowed, the user can
split the monitoring target regions into multiple contexts and call
'damon_start()' for each of the context.
If multiple monitoring threads has conflicting target regions, they will
interfere each other. Currently, avoidance of such conflict should be done by
'damon_start()' users. The synchronization would be complicated.
To make the situation simple, I will make the 'damon_start()' receive a group
of 'damon_ctx' objects and creates a group of monitoring threads for the
objects at once. This will only reduce number of 'damon_start()' calls
required to run multiple monitoring threads. In addition to this, the groups
of monitoring threads will be mutual exclusive. In other words,
'damon_start()' will fail if a group of monitoring threads that started by
other 'damon_start()' call is currently running.
This still ask the users to protect each monitoring threads by taking care in
their requests. But, because the requests are made by the user on its own,
avoiding the conflict will be quite easy. Further, intentional conflict is
also possible, though I'm unsure how the intentional conflict can be required.
The change will be made in the next spin.
Thanks,
SeongJae Park
[...]
