From: SeongJae Park <[email protected]>
Changes from Previous Version
=============================
- Wordsmith the document, comment, commit messages
- Support a scheme of max access count 0
- Use 'unsigned long' for (min|max)_sz_region
Introduction
============
DAMON[1] can be used as a primitive for data access awared memory management
optimizations. For that, users who want such optimizations should run DAMON,
read the monitoring results, analyze it, plan a new memory management scheme,
and apply the new scheme by themselves. Such efforts will be inevitable for
some complicated optimizations.
However, in many other cases, the users would simply want the system to apply a
memory management action to a memory region of a specific size having a
specific access frequency for a specific time. For example, "page out a memory
region larger than 100 MiB keeping only rare accesses more than 2 minutes", or
"Do not use THP for a memory region larger than 2 MiB rarely accessed for more
than 1 seconds".
This RFC patchset makes DAMON to handle such data access monitoring-based
operation schemes. With this change, users can do the data access aware
optimizations by simply specifying their schemes to DAMON.
[1] https://lore.kernel.org/linux-mm/[email protected]/
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
v12 of this patchset is applied.
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 the latest DAMON patchset for detailed
evaluation setup and results.
[1] https://damonitor.github.io/doc/html/latest-damos
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-damos
[3] https://damonitor.github.io/test/result/visual/latest/rec.heatmap.0.html
[4] https://damonitor.github.io/test/result/visual/latest/rec.heatmap.1.html
[5] https://damonitor.github.io/test/result/visual/latest/rec.heatmap.2.html
[6] https://damonitor.github.io/test/result/visual/latest/rec.wss_sz.html
[7] https://damonitor.github.io/test/result/visual/latest/rec.wss_time.html
[8] https://damonitor.github.io/test/result/perf/latest/html/index.html
Baseline and Complete Git Tree
==============================
The patches are based on the v5.7 plus v17 DAMON patchset[1] and Minchan's
``do_madvise()`` patch[2], which retrieved from the -next tree and slightly
modified for backporting on v5.7. You can also clone the complete git tree:
$ git clone git://github.com/sjp38/linux -b damos/rfc/v13
The web is also available:
https://github.com/sjp38/linux/releases/tag/damos/rfc/v13
There are a couple of trees for entire DAMON patchset series that future
features are included. The first one[3] contains the changes for latest
release, while the other one[4] contains the changes for next release.
[1] https://lore.kernel.org/linux-mm/[email protected]/
[2] https://lore.kernel.org/linux-mm/[email protected]/
[3] https://github.com/sjp38/linux/tree/damon/master
[4] https://github.com/sjp38/linux/tree/damon/next
Sequence Of Patches
===================
The 1st patch allows DAMON to reuse ``madvise()`` code for the actions. The
2nd patch accounts age of each region. The 3rd patch implements the handling
of the schemes in DAMON and exports a kernel space programming interface for
it. The 4th patch implements a debugfs interface for the privileged people and
user programs. The 5th patch implements schemes statistics feature for easier
tuning of the schemes and runtime access pattern analysis. The 6th patche adds
selftests for these changes, and the 7th patch adds human friendly schemes
support to the user space tool for DAMON. Finally, the 8th patch documents
this new feature in the document.
Patch History
=============
Changes from RFC v12
(https://lore.kernel.org/linux-mm/[email protected]/)
- Wordsmith the document, comment, commit messages
- Support a scheme of max access count 0
- Use 'unsigned long' for (min|max)_sz_region
Changes from RFC v11
(https://lore.kernel.org/linux-mm/[email protected]/)
- Refine the commit messages (David Hildenbrand)
- Clean up debugfs code
Changes from RFC v10
(https://lore.kernel.org/linux-mm/[email protected]/)
- Fix the wrong error handling for schemes debugfs file
- Handle the schemes stats from the user space tool
- Remove the schemes implementation plan from the document
Changes from RFC v9
(https://lore.kernel.org/linux-mm/[email protected]/)
- Rebase on v5.7
- Fix wrong comments and documents for schemes apply conditions
Changes from RFC v8
(https://lore.kernel.org/linux-mm/[email protected]/)
- Rewrite the document (Stefan Nuernberger)
- Make 'damon_for_each_*' argument order consistent (Leonard Foerster)
- Implement statistics for schemes
- Avoid races between debugfs readers and writers
- Reset age for only significant access frequency changes
- Add kernel-doc comments in damon.h
Please refer to RFC v8 for previous history
SeongJae Park (8):
mm/madvise: Export do_madvise() to external GPL modules
mm/damon: Account age of target regions
mm/damon: Implement data access monitoring-based operation schemes
mm/damon/schemes: Implement a debugfs interface
mm/damon/schemes: Implement statistics feature
mm/damon/selftests: Add 'schemes' debugfs tests
damon/tools: Support more human friendly 'schemes' control
Documentation/admin-guide/mm: Document DAMON-based operation schemes
Documentation/admin-guide/mm/damon/guide.rst | 41 ++-
Documentation/admin-guide/mm/damon/plans.rst | 24 +-
Documentation/admin-guide/mm/damon/start.rst | 11 +
Documentation/admin-guide/mm/damon/usage.rst | 124 ++++++-
include/linux/damon.h | 66 ++++
mm/damon.c | 344 +++++++++++++++++-
mm/madvise.c | 1 +
tools/damon/_convert_damos.py | 141 +++++++
tools/damon/_damon.py | 27 +-
tools/damon/damo | 7 +
tools/damon/schemes.py | 110 ++++++
.../testing/selftests/damon/debugfs_attrs.sh | 29 ++
12 files changed, 880 insertions(+), 45 deletions(-)
create mode 100755 tools/damon/_convert_damos.py
create mode 100644 tools/damon/schemes.py
--
2.17.1
From: SeongJae Park <[email protected]>
To tune the DAMON-based operation schemes, knowing how many and how
large regions are affected by each of the schemes will be helful. Those
stats could be used for not only the tuning, but also monitoring of the
working set size and the number of regions, if the scheme does not
change the program behavior too much.
For the reason, this commit implements the statistics for the schemes.
The total number and size of the regions that each scheme is applied are
exported to users via '->stat_count' and '->stat_sz' of 'struct damos'.
Admins can also check the number by reading 'schemes' debugfs file. The
last two integers now represents the stats. To allow collecting the
stats without changing the program behavior, this commit also adds new
scheme action, 'DAMOS_STAT'. Note that 'DAMOS_STAT' is not only making
no memory operation actions, but also does not reset the age of regions.
Signed-off-by: SeongJae Park <[email protected]>
---
include/linux/damon.h | 6 ++++++
mm/damon.c | 13 ++++++++++---
2 files changed, 16 insertions(+), 3 deletions(-)
diff --git a/include/linux/damon.h b/include/linux/damon.h
index 76e6ea2f97a7..f176a2b6e67c 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -73,6 +73,7 @@ struct damon_task {
* @DAMOS_PAGEOUT: Call ``madvise()`` for the region with MADV_PAGEOUT.
* @DAMOS_HUGEPAGE: Call ``madvise()`` for the region with MADV_HUGEPAGE.
* @DAMOS_NOHUGEPAGE: Call ``madvise()`` for the region with MADV_NOHUGEPAGE.
+ * @DAMOS_STAT: Do nothing but count the stat.
* @DAMOS_ACTION_LEN: Number of supported actions.
*/
enum damos_action {
@@ -81,6 +82,7 @@ enum damos_action {
DAMOS_PAGEOUT,
DAMOS_HUGEPAGE,
DAMOS_NOHUGEPAGE,
+ DAMOS_STAT, /* Do nothing but only record the stat */
DAMOS_ACTION_LEN,
};
@@ -93,6 +95,8 @@ enum damos_action {
* @min_age_region: Minimum age of target regions.
* @max_age_region: Maximum age of target regions.
* @action: &damo_action to be applied to the target regions.
+ * @stat_count: Total number of regions that this scheme is applied.
+ * @stat_sz: Total size of regions that this scheme is applied.
* @list: List head for siblings.
*
* For each aggregation interval, DAMON applies @action to monitoring target
@@ -107,6 +111,8 @@ struct damos {
unsigned int min_age_region;
unsigned int max_age_region;
enum damos_action action;
+ unsigned long stat_count;
+ unsigned long stat_sz;
struct list_head list;
};
diff --git a/mm/damon.c b/mm/damon.c
index 28b1e119e521..937b6bccb7b8 100644
--- a/mm/damon.c
+++ b/mm/damon.c
@@ -212,6 +212,8 @@ static struct damos *damon_new_scheme(
scheme->min_age_region = min_age_region;
scheme->max_age_region = max_age_region;
scheme->action = action;
+ scheme->stat_count = 0;
+ scheme->stat_sz = 0;
INIT_LIST_HEAD(&scheme->list);
return scheme;
@@ -927,6 +929,8 @@ static int damos_do_action(struct damon_task *task, struct damon_region *r,
case DAMOS_NOHUGEPAGE:
madv_action = MADV_NOHUGEPAGE;
break;
+ case DAMOS_STAT:
+ return 0;
default:
pr_warn("Wrong action %d\n", action);
return -EINVAL;
@@ -950,8 +954,11 @@ static void damon_do_apply_schemes(struct damon_ctx *c, struct damon_task *t,
continue;
if (r->age < s->min_age_region || s->max_age_region < r->age)
continue;
+ s->stat_count++;
+ s->stat_sz += sz;
damos_do_action(t, r, s->action);
- r->age = 0;
+ if (s->action != DAMOS_STAT)
+ r->age = 0;
}
}
@@ -1508,11 +1515,11 @@ static ssize_t sprint_schemes(struct damon_ctx *c, char *buf, ssize_t len)
damon_for_each_scheme(s, c) {
rc = snprintf(&buf[written], len - written,
- "%lu %lu %u %u %u %u %d\n",
+ "%lu %lu %u %u %u %u %d %lu %lu\n",
s->min_sz_region, s->max_sz_region,
s->min_nr_accesses, s->max_nr_accesses,
s->min_age_region, s->max_age_region,
- s->action);
+ s->action, s->stat_count, s->stat_sz);
if (!rc)
return -ENOMEM;
--
2.17.1
From: SeongJae Park <[email protected]>
This commit exports 'do_madvise()' to external GPL modules, so that
other modules including DAMON could use the function.
Signed-off-by: SeongJae Park <[email protected]>
---
mm/madvise.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/mm/madvise.c b/mm/madvise.c
index 1ad7522567d4..fcd951694ebc 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -1171,6 +1171,7 @@ int do_madvise(struct task_struct *target_task, struct mm_struct *mm,
return error;
}
+EXPORT_SYMBOL_GPL(do_madvise);
SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior)
{
--
2.17.1
From: SeongJae Park <[email protected]>
DAMON can be used as a primitive for data access pattern aware memory
management optimizations. However, users who want such optimizations
should run DAMON, read the monitoring results, analyze it, plan a new
memory management scheme, and apply the new scheme by themselves. It
would not be too hard, but still require some level of effort. For
complicated optimizations, this effort is inevitable.
That said, in many cases, users would simply want to apply an actions to
a memory region of a specific size having a specific access frequency
for a specific time. For example, "page out a memory region larger than
100 MiB but having a low access frequency more than 10 minutes", or "Use
THP for a memory region larger than 2 MiB having a high access frequency
for more than 2 seconds".
For such optimizations, users will need to first account the age of each
region themselves. To reduce such efforts, this commit implements a
simple age account of each region in DAMON. For each aggregation step,
DAMON compares the access frequency with that from last aggregation and
reset the age of the region if the change is significant. Else, the age
is incremented. Also, in case of the merge of regions, the region
size-weighted average of the ages is set as the age of merged new
region.
Signed-off-by: SeongJae Park <[email protected]>
---
include/linux/damon.h | 10 ++++++++++
mm/damon.c | 20 +++++++++++++++++---
2 files changed, 27 insertions(+), 3 deletions(-)
diff --git a/include/linux/damon.h b/include/linux/damon.h
index b0e7e31a22b3..e94dab4edab6 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -31,12 +31,22 @@ struct damon_addr_range {
* @sampling_addr: Address of the sample for the next access check.
* @nr_accesses: Access frequency of this region.
* @list: List head for siblings.
+ * @age: Age of this region.
+ * @last_nr_accesses: Internal value for age calculation.
+ *
+ * @age is initially zero, increased for each aggregation interval, and reset
+ * to zero again if the access frequency is significantly changed. If two
+ * regions are merged into a new region, both @nr_accesses and @age of the new
+ * region are set as region size-weighted average of those of the two regions.
*/
struct damon_region {
struct damon_addr_range ar;
unsigned long sampling_addr;
unsigned int nr_accesses;
struct list_head list;
+
+ unsigned int age;
+ unsigned int last_nr_accesses;
};
/**
diff --git a/mm/damon.c b/mm/damon.c
index 0f906126d21f..f46844540b37 100644
--- a/mm/damon.c
+++ b/mm/damon.c
@@ -107,6 +107,9 @@ static struct damon_region *damon_new_region(unsigned long start,
region->nr_accesses = 0;
INIT_LIST_HEAD(®ion->list);
+ region->age = 0;
+ region->last_nr_accesses = 0;
+
return region;
}
@@ -815,6 +818,7 @@ static void kdamond_reset_aggregated(struct damon_ctx *c)
damon_write_rbuf(c, &r->nr_accesses,
sizeof(r->nr_accesses));
trace_damon_aggregated(t, r, nr);
+ r->last_nr_accesses = r->nr_accesses;
r->nr_accesses = 0;
}
}
@@ -828,9 +832,11 @@ static void kdamond_reset_aggregated(struct damon_ctx *c)
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));
+ unsigned long sz_l = sz_damon_region(l), sz_r = sz_damon_region(r);
+
+ l->nr_accesses = (l->nr_accesses * sz_l + r->nr_accesses * sz_r) /
+ (sz_l + sz_r);
+ l->age = (l->age * sz_l + r->age * sz_r) / (sz_l + sz_r);
l->ar.end = r->ar.end;
damon_destroy_region(r);
}
@@ -850,6 +856,11 @@ static void damon_merge_regions_of(struct damon_task *t, unsigned int thres,
struct damon_region *r, *prev = NULL, *next;
damon_for_each_region_safe(r, next, t) {
+ if (diff_of(r->nr_accesses, r->last_nr_accesses) > thres)
+ r->age = 0;
+ else
+ r->age++;
+
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)
@@ -893,6 +904,9 @@ static void damon_split_region_at(struct damon_ctx *ctx,
new = damon_new_region(r->ar.start + sz_r, r->ar.end);
r->ar.end = new->ar.start;
+ new->age = r->age;
+ new->last_nr_accesses = r->last_nr_accesses;
+
damon_insert_region(new, r, damon_next_region(r));
}
--
2.17.1
From: SeongJae Park <[email protected]>
This commit implements 'schemes' subcommand of the damon userspace tool.
It can be used to describe and apply the data access monitoring-based
operation schemes in more human friendly fashion.
Signed-off-by: SeongJae Park <[email protected]>
---
tools/damon/_convert_damos.py | 141 ++++++++++++++++++++++++++++++++++
tools/damon/_damon.py | 27 +++++--
tools/damon/damo | 7 ++
tools/damon/schemes.py | 110 ++++++++++++++++++++++++++
4 files changed, 280 insertions(+), 5 deletions(-)
create mode 100755 tools/damon/_convert_damos.py
create mode 100644 tools/damon/schemes.py
diff --git a/tools/damon/_convert_damos.py b/tools/damon/_convert_damos.py
new file mode 100755
index 000000000000..0fd84b3701c9
--- /dev/null
+++ b/tools/damon/_convert_damos.py
@@ -0,0 +1,141 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+
+"""
+Change human readable data access monitoring-based operation schemes to the low
+level input for the '<debugfs>/damon/schemes' file. Below is an example of the
+schemes written in the human readable format:
+
+ # format is:
+ # <min/max size> <min/max frequency (0-100)> <min/max age> <action>
+ #
+ # B/K/M/G/T for Bytes/KiB/MiB/GiB/TiB
+ # us/ms/s/m/h/d for micro-seconds/milli-seconds/seconds/minutes/hours/days
+ # 'min/max' for possible min/max value.
+
+ # if a region keeps a high access frequency for >=100ms, put the region on
+ # the head of the LRU list (call madvise() with MADV_WILLNEED).
+ min max 80 max 100ms max willneed
+
+ # if a region keeps a low access frequency for >=200ms and <=one hour, put
+ # the region on the tail of the LRU list (call madvise() with MADV_COLD).
+ min max 10 20 200ms 1h cold
+
+ # if a region keeps a very low access frequency for >=60 seconds, swap out
+ # the region immediately (call madvise() with MADV_PAGEOUT).
+ min max 0 10 60s max pageout
+
+ # if a region of a size >=2MiB keeps a very high access frequency for
+ # >=100ms, let the region to use huge pages (call madvise() with
+ # MADV_HUGEPAGE).
+ 2M max 90 100 100ms max hugepage
+
+ # If a regions of a size >=2MiB keeps small access frequency for >=100ms,
+ # avoid the region using huge pages (call madvise() with MADV_NOHUGEPAGE).
+ 2M max 0 25 100ms max nohugepage
+"""
+
+import argparse
+import platform
+
+uint_max = 2**32 - 1
+ulong_max = 2**64 - 1
+if platform.architecture()[0] != '64bit':
+ ulong_max = 2**32 - 1
+
+unit_to_bytes = {'B': 1, 'K': 1024, 'M': 1024 * 1024, 'G': 1024 * 1024 * 1024,
+ 'T': 1024 * 1024 * 1024 * 1024}
+
+def text_to_bytes(txt):
+ if txt == 'min':
+ return 0
+ if txt == 'max':
+ return ulong_max
+
+ unit = txt[-1]
+ number = float(txt[:-1])
+ return int(number * unit_to_bytes[unit])
+
+unit_to_usecs = {'us': 1, 'ms': 1000, 's': 1000 * 1000, 'm': 60 * 1000 * 1000,
+ 'h': 60 * 60 * 1000 * 1000, 'd': 24 * 60 * 60 * 1000 * 1000}
+
+def text_to_aggr_intervals(txt, aggr_interval):
+ if txt == 'min':
+ return 0
+ if txt == 'max':
+ return uint_max
+
+ unit = txt[-2:]
+ if unit in ['us', 'ms']:
+ number = float(txt[:-2])
+ else:
+ unit = txt[-1]
+ number = float(txt[:-1])
+ return int(number * unit_to_usecs[unit]) / aggr_interval
+
+damos_action_to_int = {'DAMOS_WILLNEED': 0, 'DAMOS_COLD': 1,
+ 'DAMOS_PAGEOUT': 2, 'DAMOS_HUGEPAGE': 3, 'DAMOS_NOHUGEPAGE': 4,
+ 'DAMOS_STAT': 5}
+
+def text_to_damos_action(txt):
+ return damos_action_to_int['DAMOS_' + txt.upper()]
+
+def text_to_nr_accesses(txt, max_nr_accesses):
+ if txt == 'min':
+ return 0
+ if txt == 'max':
+ return max_nr_accesses
+
+ return int(float(txt) * max_nr_accesses / 100)
+
+def debugfs_scheme(line, sample_interval, aggr_interval):
+ fields = line.split()
+ if len(fields) != 7:
+ print('wrong input line: %s' % line)
+ exit(1)
+
+ limit_nr_accesses = aggr_interval / sample_interval
+ try:
+ min_sz = text_to_bytes(fields[0])
+ max_sz = text_to_bytes(fields[1])
+ min_nr_accesses = text_to_nr_accesses(fields[2], limit_nr_accesses)
+ max_nr_accesses = text_to_nr_accesses(fields[3], limit_nr_accesses)
+ min_age = text_to_aggr_intervals(fields[4], aggr_interval)
+ max_age = text_to_aggr_intervals(fields[5], aggr_interval)
+ action = text_to_damos_action(fields[6])
+ except:
+ print('wrong input field')
+ raise
+ return '%d\t%d\t%d\t%d\t%d\t%d\t%d' % (min_sz, max_sz, min_nr_accesses,
+ max_nr_accesses, min_age, max_age, action)
+
+def convert(schemes_file, sample_interval, aggr_interval):
+ lines = []
+ with open(schemes_file, 'r') as f:
+ for line in f:
+ if line.startswith('#'):
+ continue
+ line = line.strip()
+ if line == '':
+ continue
+ lines.append(debugfs_scheme(line, sample_interval, aggr_interval))
+ return '\n'.join(lines)
+
+def main():
+ parser = argparse.ArgumentParser()
+ parser.add_argument('input', metavar='<file>',
+ help='input file describing the schemes')
+ parser.add_argument('-s', '--sample', metavar='<interval>', type=int,
+ default=5000, help='sampling interval (us)')
+ parser.add_argument('-a', '--aggr', metavar='<interval>', type=int,
+ default=100000, help='aggregation interval (us)')
+ args = parser.parse_args()
+
+ schemes_file = args.input
+ sample_interval = args.sample
+ aggr_interval = args.aggr
+
+ print(convert(schemes_file, sample_interval, aggr_interval))
+
+if __name__ == '__main__':
+ main()
diff --git a/tools/damon/_damon.py b/tools/damon/_damon.py
index 2a08468ad27e..3620ef12a5ea 100644
--- a/tools/damon/_damon.py
+++ b/tools/damon/_damon.py
@@ -10,6 +10,7 @@ import subprocess
debugfs_attrs = None
debugfs_record = None
+debugfs_schemes = None
debugfs_pids = None
debugfs_monitor_on = None
@@ -33,8 +34,9 @@ class Attrs:
max_nr_regions = None
rbuf_len = None
rfile_path = None
+ schemes = None
- def __init__(self, s, a, r, n, x, l, f):
+ def __init__(self, s, a, r, n, x, l, f, c):
self.sample_interval = s
self.aggr_interval = a
self.regions_update_interval = r
@@ -42,12 +44,13 @@ class Attrs:
self.max_nr_regions = x
self.rbuf_len = l
self.rfile_path = f
+ self.schemes = c
def __str__(self):
- return "%s %s %s %s %s %s %s" % (self.sample_interval,
+ return "%s %s %s %s %s %s %s\n%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)
+ self.rfile_path, self.schemes)
def attr_str(self):
return "%s %s %s %s %s " % (self.sample_interval, self.aggr_interval,
@@ -66,6 +69,9 @@ class Attrs:
debugfs_record), shell=True, executable='/bin/bash')
if ret:
return ret
+ return subprocess.call('echo %s > %s' % (
+ self.schemes.replace('\n', ' '), debugfs_schemes), shell=True,
+ executable='/bin/bash')
def current_attrs():
with open(debugfs_attrs, 'r') as f:
@@ -77,17 +83,26 @@ def current_attrs():
attrs.append(int(rattrs[0]))
attrs.append(rattrs[1])
+ with open(debugfs_schemes, 'r') as f:
+ schemes = f.read()
+
+ # The last two fields in each line are statistics. Remove those.
+ schemes = [' '.join(x.split()[:-2]) for x in schemes.strip().split('\n')]
+ attrs.append('\n'.join(schemes))
+
return Attrs(*attrs)
def chk_update_debugfs(debugfs):
global debugfs_attrs
global debugfs_record
+ global debugfs_schemes
global debugfs_pids
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_schemes = os.path.join(debugfs_damon, 'schemes')
debugfs_pids = os.path.join(debugfs_damon, 'pids')
debugfs_monitor_on = os.path.join(debugfs_damon, 'monitor_on')
@@ -95,7 +110,8 @@ def chk_update_debugfs(debugfs):
print("damon debugfs dir (%s) not found", debugfs_damon)
exit(1)
- for f in [debugfs_attrs, debugfs_record, debugfs_pids, debugfs_monitor_on]:
+ for f in [debugfs_attrs, debugfs_record, debugfs_schemes, debugfs_pids,
+ debugfs_monitor_on]:
if not os.path.isfile(f):
print("damon debugfs file (%s) not found" % f)
exit(1)
@@ -111,8 +127,9 @@ def cmd_args_to_attrs(args):
if not os.path.isabs(args.out):
args.out = os.path.join(os.getcwd(), args.out)
rfile_path = args.out
+ schemes = args.schemes
return Attrs(sample_interval, aggr_interval, regions_update_interval,
- min_nr_regions, max_nr_regions, rbuf_len, rfile_path)
+ min_nr_regions, max_nr_regions, rbuf_len, rfile_path, schemes)
def set_attrs_argparser(parser):
parser.add_argument('-d', '--debugfs', metavar='<debugfs>', type=str,
diff --git a/tools/damon/damo b/tools/damon/damo
index 58e1099ae5fc..ce7180069bef 100755
--- a/tools/damon/damo
+++ b/tools/damon/damo
@@ -5,6 +5,7 @@ import argparse
import record
import report
+import schemes
class SubCmdHelpFormatter(argparse.RawDescriptionHelpFormatter):
def _format_action(self, action):
@@ -25,6 +26,10 @@ parser_record = subparser.add_parser('record',
help='record data accesses of the given target processes')
record.set_argparser(parser_record)
+parser_schemes = subparser.add_parser('schemes',
+ help='apply operation schemes to the given target process')
+schemes.set_argparser(parser_schemes)
+
parser_report = subparser.add_parser('report',
help='report the recorded data accesses in the specified form')
report.set_argparser(parser_report)
@@ -33,5 +38,7 @@ args = parser.parse_args()
if args.command == 'record':
record.main(args)
+elif args.command == 'schemes':
+ schemes.main(args)
elif args.command == 'report':
report.main(args)
diff --git a/tools/damon/schemes.py b/tools/damon/schemes.py
new file mode 100644
index 000000000000..9f369db7d12e
--- /dev/null
+++ b/tools/damon/schemes.py
@@ -0,0 +1,110 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+
+"""
+Apply given operation schemes to the target process.
+"""
+
+import argparse
+import os
+import signal
+import subprocess
+import time
+
+import _convert_damos
+import _damon
+
+def run_damon(target, is_target_cmd, attrs, old_attrs):
+ 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()))
+ for line in attrs.schemes.split('\n'):
+ print('# scheme: %s' % line)
+ if is_target_cmd:
+ p = subprocess.Popen(target, shell=True, executable='/bin/bash')
+ target = p.pid
+ if _damon.set_target_pid(target):
+ print('pid 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():
+ 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)
+
+ 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():
+ 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('-c', '--schemes', metavar='<file>', type=str,
+ default='damon.schemes',
+ help='data access monitoring-based operation schemes')
+
+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.rbuf = 0
+ args.out = 'null'
+ args.schemes = _convert_damos.convert(args.schemes, args.sample, args.aggr)
+ 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'):
+ run_damon(target, True, new_attrs, orig_attrs)
+ else:
+ try:
+ pid = int(target)
+ except:
+ print('target \'%s\' is neither a command, nor a pid' % target)
+ exit(1)
+ run_damon(target, False, new_attrs, orig_attrs)
+
+if __name__ == '__main__':
+ main()
--
2.17.1
From: SeongJae Park <[email protected]>
This commit implements a debugfs interface for the data access
monitoring oriented memory management schemes. It is supposed to be
used by administrators and/or privileged user space programs. Users can
read and update the rules using ``<debugfs>/damon/schemes`` file. The
format is::
<min/max size> <min/max access frequency> <min/max age> <action>
Signed-off-by: SeongJae Park <[email protected]>
---
mm/damon.c | 172 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 170 insertions(+), 2 deletions(-)
diff --git a/mm/damon.c b/mm/damon.c
index c08b8c80c517..28b1e119e521 100644
--- a/mm/damon.c
+++ b/mm/damon.c
@@ -194,6 +194,29 @@ static void damon_destroy_task(struct damon_task *t)
damon_free_task(t);
}
+static struct damos *damon_new_scheme(
+ unsigned long min_sz_region, unsigned long max_sz_region,
+ unsigned int min_nr_accesses, unsigned int max_nr_accesses,
+ unsigned int min_age_region, unsigned int max_age_region,
+ enum damos_action action)
+{
+ struct damos *scheme;
+
+ scheme = kmalloc(sizeof(*scheme), GFP_KERNEL);
+ if (!scheme)
+ return NULL;
+ scheme->min_sz_region = min_sz_region;
+ scheme->max_sz_region = max_sz_region;
+ scheme->min_nr_accesses = min_nr_accesses;
+ scheme->max_nr_accesses = max_nr_accesses;
+ scheme->min_age_region = min_age_region;
+ scheme->max_age_region = max_age_region;
+ scheme->action = action;
+ INIT_LIST_HEAD(&scheme->list);
+
+ return scheme;
+}
+
static void damon_add_scheme(struct damon_ctx *ctx, struct damos *s)
{
list_add_tail(&s->list, &ctx->schemes_list);
@@ -1477,6 +1500,145 @@ static ssize_t debugfs_monitor_on_write(struct file *file,
return ret;
}
+static ssize_t sprint_schemes(struct damon_ctx *c, char *buf, ssize_t len)
+{
+ struct damos *s;
+ int written = 0;
+ int rc;
+
+ damon_for_each_scheme(s, c) {
+ rc = snprintf(&buf[written], len - written,
+ "%lu %lu %u %u %u %u %d\n",
+ s->min_sz_region, s->max_sz_region,
+ s->min_nr_accesses, s->max_nr_accesses,
+ s->min_age_region, s->max_age_region,
+ s->action);
+ if (!rc)
+ return -ENOMEM;
+
+ written += rc;
+ }
+ return written;
+}
+
+static ssize_t debugfs_schemes_read(struct file *file, char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ struct damon_ctx *ctx = &damon_user_ctx;
+ char *kbuf;
+ ssize_t len;
+
+ kbuf = kmalloc(count, GFP_KERNEL);
+ if (!kbuf)
+ return -ENOMEM;
+
+ mutex_lock(&ctx->kdamond_lock);
+ len = sprint_schemes(ctx, kbuf, count);
+ mutex_unlock(&ctx->kdamond_lock);
+ if (len < 0)
+ goto out;
+ len = simple_read_from_buffer(buf, count, ppos, kbuf, len);
+
+out:
+ kfree(kbuf);
+ return len;
+}
+
+static void free_schemes_arr(struct damos **schemes, ssize_t nr_schemes)
+{
+ ssize_t i;
+
+ for (i = 0; i < nr_schemes; i++)
+ kfree(schemes[i]);
+ kfree(schemes);
+}
+
+/*
+ * Converts a string into an array of struct damos pointers
+ *
+ * Returns an array of struct damos pointers that converted if the conversion
+ * success, or NULL otherwise.
+ */
+static struct damos **str_to_schemes(const char *str, ssize_t len,
+ ssize_t *nr_schemes)
+{
+ struct damos *scheme, **schemes;
+ const int max_nr_schemes = 256;
+ int pos = 0, parsed, ret;
+ unsigned long min_sz, max_sz;
+ unsigned int min_nr_a, max_nr_a, min_age, max_age;
+ unsigned int action;
+
+ schemes = kmalloc_array(max_nr_schemes, sizeof(scheme),
+ GFP_KERNEL);
+ if (!schemes)
+ return NULL;
+
+ *nr_schemes = 0;
+ while (pos < len && *nr_schemes < max_nr_schemes) {
+ ret = sscanf(&str[pos], "%lu %lu %u %u %u %u %u%n",
+ &min_sz, &max_sz, &min_nr_a, &max_nr_a,
+ &min_age, &max_age, &action, &parsed);
+ if (ret != 7)
+ break;
+ if (action >= DAMOS_ACTION_LEN) {
+ pr_err("wrong action %d\n", action);
+ goto fail;
+ }
+
+ pos += parsed;
+ scheme = damon_new_scheme(min_sz, max_sz, min_nr_a, max_nr_a,
+ min_age, max_age, action);
+ if (!scheme)
+ goto fail;
+
+ schemes[*nr_schemes] = scheme;
+ *nr_schemes += 1;
+ }
+ return schemes;
+fail:
+ free_schemes_arr(schemes, *nr_schemes);
+ return NULL;
+}
+
+static ssize_t debugfs_schemes_write(struct file *file, const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ struct damon_ctx *ctx = &damon_user_ctx;
+ char *kbuf;
+ struct damos **schemes;
+ ssize_t nr_schemes = 0, ret = count;
+ int err;
+
+ kbuf = user_input_str(buf, count, ppos);
+ if (IS_ERR(kbuf))
+ return PTR_ERR(kbuf);
+
+ schemes = str_to_schemes(kbuf, ret, &nr_schemes);
+ if (!schemes) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ mutex_lock(&ctx->kdamond_lock);
+ if (ctx->kdamond) {
+ ret = -EBUSY;
+ goto unlock_out;
+ }
+
+ err = damon_set_schemes(ctx, schemes, nr_schemes);
+ if (err)
+ ret = err;
+ else
+ nr_schemes = 0;
+unlock_out:
+ mutex_unlock(&ctx->kdamond_lock);
+ free_schemes_arr(schemes, nr_schemes);
+out:
+ kfree(kbuf);
+ return ret;
+}
+
static ssize_t damon_sprint_pids(struct damon_ctx *ctx, char *buf, ssize_t len)
{
struct damon_task *t;
@@ -1695,6 +1857,12 @@ static const struct file_operations pids_fops = {
.write = debugfs_pids_write,
};
+static const struct file_operations schemes_fops = {
+ .owner = THIS_MODULE,
+ .read = debugfs_schemes_read,
+ .write = debugfs_schemes_write,
+};
+
static const struct file_operations record_fops = {
.owner = THIS_MODULE,
.read = debugfs_record_read,
@@ -1711,10 +1879,10 @@ static struct dentry *debugfs_root;
static int __init damon_debugfs_init(void)
{
- const char * const file_names[] = {"attrs", "record",
+ const char * const file_names[] = {"attrs", "record", "schemes",
"pids", "monitor_on"};
const struct file_operations *fops[] = {&attrs_fops, &record_fops,
- &pids_fops, &monitor_on_fops};
+ &schemes_fops, &pids_fops, &monitor_on_fops};
int i;
debugfs_root = debugfs_create_dir("damon", NULL);
--
2.17.1
From: SeongJae Park <[email protected]>
This commit documents DAMON-based operation schemes in the DAMON
document.
Signed-off-by: SeongJae Park <[email protected]>
---
Documentation/admin-guide/mm/damon/guide.rst | 41 +++++-
Documentation/admin-guide/mm/damon/plans.rst | 24 +---
Documentation/admin-guide/mm/damon/start.rst | 11 ++
Documentation/admin-guide/mm/damon/usage.rst | 124 +++++++++++++++++--
4 files changed, 165 insertions(+), 35 deletions(-)
diff --git a/Documentation/admin-guide/mm/damon/guide.rst b/Documentation/admin-guide/mm/damon/guide.rst
index 77775b73f015..783fef558f3b 100644
--- a/Documentation/admin-guide/mm/damon/guide.rst
+++ b/Documentation/admin-guide/mm/damon/guide.rst
@@ -53,6 +53,11 @@ 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 the access pattern is very frequently changing so that you cannot figure out
+what is the performance important region using your human eye, `Automated
+DAMON-based Memory Operations`_ might help the case owing to its machine-level
+microscope view.
+
If you still want to absorb more benefits, you should develop `Personalized
DAMON Application`_ for your special case.
@@ -158,6 +163,36 @@ hot object.
The chronological changes of working set size.
+Automated DAMON-based Memory Operations
+---------------------------------------
+
+Though `Manual Program Optimization` works well in many cases and DAMON can
+help it, modifying the source code is not a good option in many cases. First
+of all, the source code could be too old or unavailable. And, many workloads
+will have complex data access patterns that even hard to distinguish hot memory
+objects and cold memory objects with the human eye. Finding the mapping from
+the visualized access pattern to the source code and injecting the hinting
+system calls inside the code will also be quite challenging.
+
+By using DAMON-based operation schemes (DAMOS) via ``damo schemes``, you will
+be able to easily optimize your workload in such a case. Our example schemes
+called 'efficient THP' and 'proactive reclamation' achieved significant speedup
+and memory space saves against 25 realistic workloads [2]_.
+
+That said, note that you need careful tune of the schemes (e.g., target region
+size and age) and monitoring attributes for the successful use of this
+approach. Because the optimal values of the parameters will be dependent on
+each system and workload, misconfiguring the parameters could result in worse
+memory management.
+
+For the tuning, you could measure the performance metrics such as IPC, TLB
+misses, and swap in/out events and adjusts the parameters based on their
+changes. The total number and the total size of the regions that each scheme
+is applied, which are provided via the debugfs interface and the programming
+interface can also be useful. Writing a program automating this optimal
+parameter could be an option.
+
+
Personalized DAMON Application
------------------------------
@@ -183,9 +218,9 @@ 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]_.
+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/
diff --git a/Documentation/admin-guide/mm/damon/plans.rst b/Documentation/admin-guide/mm/damon/plans.rst
index e3aa5ab96c29..765344f02eb3 100644
--- a/Documentation/admin-guide/mm/damon/plans.rst
+++ b/Documentation/admin-guide/mm/damon/plans.rst
@@ -4,26 +4,4 @@
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]/
+TBD.
diff --git a/Documentation/admin-guide/mm/damon/start.rst b/Documentation/admin-guide/mm/damon/start.rst
index 4b861509565d..ae61ca75dc80 100644
--- a/Documentation/admin-guide/mm/damon/start.rst
+++ b/Documentation/admin-guide/mm/damon/start.rst
@@ -112,6 +112,17 @@ workloads at external web pages [1]_ [2]_ [3]_.
The chronological changes of working set size.
+
+Data Access Pattern Aware Memory Management
+===========================================
+
+Below three commands make every memory region of size >=4K that doesn't
+accessed for >=60 seconds in your workload to be swapped out. ::
+
+ $ echo "#min-size max-size min-acc max-acc min-age max-age action" > scheme
+ $ echo "4K max 0 0 60s max pageout" >> scheme
+ $ damo schemes -c my_thp_scheme <pid of your workload>
+
.. [1] https://damonitor.github.io/test/result/visual/latest/rec.heatmap.1.png.html
.. [2] https://damonitor.github.io/test/result/visual/latest/rec.wss_sz.png.html
.. [3] 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
index 9d71f04d12ee..153f07da9368 100644
--- a/Documentation/admin-guide/mm/damon/usage.rst
+++ b/Documentation/admin-guide/mm/damon/usage.rst
@@ -218,11 +218,70 @@ Similar to that of ``heats --heatmap``, it also supports 'gnuplot' based simple
visualization of the distribution via ``--plot`` option.
+DAMON-based Operation Schemes
+-----------------------------
+
+The ``schemes`` subcommand allows users to do DAMON-based memory management
+optimizations in a few seconds. Similar to ``record``, it receives monitoring
+attributes and target. However, in addition to those, ``schemes`` receives
+data access pattern-based memory operation schemes, which describes what memory
+operation action should be applied to memory regions showing specific data
+access pattern. Then, it starts the data access monitoring and automatically
+applies the schemes to the targets.
+
+The operation schemes should be saved in a text file in below format and passed
+to ``schemes`` subcommand via ``--schemes`` option. ::
+
+ min-size max-size min-acc max-acc min-age max-age action
+
+The format also supports comments, several units for size and age of regions,
+and human readable action names. Currently supported operation actions are
+``willneed``, ``cold``, ``pageout``, ``hugepage`` and ``nohugepage``. Each of
+the actions works same to the madvise() system call hints having the name.
+Please also note that the range is inclusive (closed interval), and ``0`` for
+max values means infinite. Below example schemes are possible. ::
+
+ # format is:
+ # <min/max size> <min/max frequency (0-100)> <min/max age> <action>
+ #
+ # B/K/M/G/T for Bytes/KiB/MiB/GiB/TiB
+ # us/ms/s/m/h/d for micro-seconds/milli-seconds/seconds/minutes/hours/days
+ # 'min/max' for possible min/max value.
+
+ # if a region keeps a high access frequency for >=100ms, put the region on
+ # the head of the LRU list (call madvise() with MADV_WILLNEED).
+ min max 80 max 100ms max willneed
+
+ # if a region keeps a low access frequency for >=200ms and <=one hour, put
+ # the region on the tail of the LRU list (call madvise() with MADV_COLD).
+ min max 10 20 200ms 1h cold
+
+ # if a region keeps a very low access frequency for >=60 seconds, swap out
+ # the region immediately (call madvise() with MADV_PAGEOUT).
+ min max 0 10 60s max pageout
+
+ # if a region of a size >=2MiB keeps a very high access frequency for
+ # >=100ms, let the region to use huge pages (call madvise() with
+ # MADV_HUGEPAGE).
+ 2M max 90 100 100ms max hugepage
+
+ # If a regions of a size >=2MiB keeps small access frequency for >=100ms,
+ # avoid the region using huge pages (call madvise() with MADV_NOHUGEPAGE).
+ 2M max 0 25 100ms max nohugepage
+
+For example, you can make a running process named 'foo' to use huge pages for
+memory regions keeping 2MB or larger size and having very high access frequency
+for at least 100 milliseconds using below commands::
+
+ $ echo "2M max 90 max 100ms max hugepage" > my_thp_scheme
+ $ ./damo schemes --schemes my_thp_scheme `pidof foo`
+
+
debugfs Interface
=================
-DAMON exports four files, ``attrs``, ``pids``, ``record``, and ``monitor_on``
-under its debugfs directory, ``<debugfs>/damon/``.
+DAMON exports five files, ``attrs``, ``pids``, ``record``, ``schemes`` and
+``monitor_on`` under its debugfs directory, ``<debugfs>/damon/``.
Attributes
@@ -274,16 +333,63 @@ saved in ``/damon.data``. ::
The recording can be disabled by setting the buffer size zero.
+Schemes
+-------
+
+For usual DAMON-based data access aware memory management optimizations, users
+would simply want the system to apply a memory management action to a memory
+region of a specific size having a specific access frequency for a specific
+time. DAMON receives such formalized operation schemes from the user and
+applies those to the target processes. It also counts the total number and
+size of regions that each scheme is applied. This statistics can be used for
+online analysis or tuning of the schemes.
+
+Users can get and set the schemes by reading from and writing to ``schemes``
+debugfs file. Reading the file also shows the statistics of each scheme. To
+the file, each of the schemes should be represented in each line in below form:
+
+ min-size max-size min-acc max-acc min-age max-age action
+
+Note that the ranges are closed interval. Bytes for the size of regions
+(``min-size`` and ``max-size``), number of monitored accesses per aggregate
+interval for access frequency (``min-acc`` and ``max-acc``), number of
+aggregate intervals for the age of regions (``min-age`` and ``max-age``), and a
+predefined integer for memory management actions should be used. The supported
+numbers and their meanings are as below.
+
+ - 0: Call ``madvise()`` for the region with ``MADV_WILLNEED``
+ - 1: Call ``madvise()`` for the region with ``MADV_COLD``
+ - 2: Call ``madvise()`` for the region with ``MADV_PAGEOUT``
+ - 3: Call ``madvise()`` for the region with ``MADV_HUGEPAGE``
+ - 4: Call ``madvise()`` for the region with ``MADV_NOHUGEPAGE``
+ - 5: Do nothing but count the statistics
+
+You can disable schemes by simply writing an empty string to the file. For
+example, below commands applies a scheme saying "If a memory region of size in
+[4KiB, 8KiB] is showing accesses per aggregate interval in [0, 5] for aggregate
+interval in [10, 20], page out the region", check the entered scheme again, and
+finally remove the scheme. ::
+
+ # cd <debugfs>/damon
+ # echo "4096 8192 0 5 10 20 2" > schemes
+ # cat schemes
+ 4096 8192 0 5 10 20 2 0 0
+ # echo > schemes
+
+The last two integers in the 4th line of above example is the total number and
+the total size of the regions that the scheme is applied.
+
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 and recording 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::
+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.
+Recording and schemes will also start work if requested before. 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
--
2.17.1
From: SeongJae Park <[email protected]>
This commit adds simple selftets for 'schemes' debugfs file of DAMON.
Signed-off-by: SeongJae Park <[email protected]>
---
.../testing/selftests/damon/debugfs_attrs.sh | 29 +++++++++++++++++++
1 file changed, 29 insertions(+)
diff --git a/tools/testing/selftests/damon/debugfs_attrs.sh b/tools/testing/selftests/damon/debugfs_attrs.sh
index d5188b0f71b1..4aeb2037a67e 100755
--- a/tools/testing/selftests/damon/debugfs_attrs.sh
+++ b/tools/testing/selftests/damon/debugfs_attrs.sh
@@ -97,6 +97,35 @@ fi
echo $ORIG_CONTENT > $file
+# Test schemes file
+file="$DBGFS/schemes"
+
+ORIG_CONTENT=$(cat $file)
+echo "1 2 3 4 5 6 3" > $file
+if [ $? -ne 0 ]
+then
+ echo "$file write fail"
+ echo $ORIG_CONTENT > $file
+ exit 1
+fi
+
+echo "1 2
+3 4 5 6 3" > $file
+if [ $? -eq 0 ]
+then
+ echo "$file multi line write success (expected fail)"
+ echo $ORIG_CONTENT > $file
+ exit 1
+fi
+
+echo > $file
+if [ $? -ne 0 ]
+then
+ echo "$file empty string writing fail"
+ echo $ORIG_CONTENT > $file
+ exit 1
+fi
+
# Test pids file
file="$DBGFS/pids"
--
2.17.1
