Changes from RFC v1
(https://lore.kernel.org/r/[email protected])
- Rename __damon_pa_young() to damon_folio_young_one()
- Mark the folio as old from the filter for the next check
DAMON allows users to specify desired ranges of overhead and accuracy of
the monitoring, and do its best effort to make most lightweight and
accurate results. A recent discussion for tiered memory management
support from DAMON[1] revealed that the best effort accuracy may not
suffice in some use cases, while increasing the minimum accuracy can
incur too high overhead. The discussion further concluded finding
memory regions of specific access pattern via DAMON first, and then
double checking the access of the region again in finer granularity
could help increasing the accuracy while keeping the low overhead.
Add a new type of DAMOS filter, namely YOUNG for such a case. Like anon
and memcg, the type of filter is applied to each page of the memory
region of DAMOS target memory region, and check if the page is accessed
since the last check. Because this is a filter type that applied in
page granularity, the support depends on DAMON operations set. Because
there are expected usages of this filter for physical address space
based DAMOS usage[1], implement the support for only DAMON operations
set for the physical address space, paddr.
[1] https://lore.kernel.org/r/[email protected]
SeongJae Park (4):
mm/damon/paddr: implement damon_folio_young()
mm/damon/paddr: implement damon_folio_mkold()
mm/damon: add DAMOS filter type YOUNG
mm/damon/paddr: support DAMOS filter type YOUNG
include/linux/damon.h | 2 ++
mm/damon/paddr.c | 64 +++++++++++++++++++++++++---------------
mm/damon/sysfs-schemes.c | 1 +
3 files changed, 43 insertions(+), 24 deletions(-)
base-commit: 13043cde46a19e72d37965b67b74e564623f65e7
--
2.39.2
damon_pa_young() receives physical address, get the folio covering the
address, and show if the folio is accessed since the last check. Split
the internal logic for checking access to the given folio, for future
reuse of the logic from code that already got the folio of the address
of the question. Also, change the rmap walker function's name from
__damon_pa_young() to damon_folio_young_one(), for consistent naming.
Signed-off-by: SeongJae Park <[email protected]>
---
mm/damon/paddr.c | 32 +++++++++++++++++++-------------
1 file changed, 19 insertions(+), 13 deletions(-)
diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
index 5e6dc312072c..25c3ba2a9eaf 100644
--- a/mm/damon/paddr.c
+++ b/mm/damon/paddr.c
@@ -79,8 +79,8 @@ static void damon_pa_prepare_access_checks(struct damon_ctx *ctx)
}
}
-static bool __damon_pa_young(struct folio *folio, struct vm_area_struct *vma,
- unsigned long addr, void *arg)
+static bool damon_folio_young_one(struct folio *folio,
+ struct vm_area_struct *vma, unsigned long addr, void *arg)
{
bool *accessed = arg;
DEFINE_FOLIO_VMA_WALK(pvmw, folio, vma, addr, 0);
@@ -111,38 +111,44 @@ static bool __damon_pa_young(struct folio *folio, struct vm_area_struct *vma,
return *accessed == false;
}
-static bool damon_pa_young(unsigned long paddr, unsigned long *folio_sz)
+static bool damon_folio_young(struct folio *folio)
{
- struct folio *folio = damon_get_folio(PHYS_PFN(paddr));
bool accessed = false;
struct rmap_walk_control rwc = {
.arg = &accessed,
- .rmap_one = __damon_pa_young,
+ .rmap_one = damon_folio_young_one,
.anon_lock = folio_lock_anon_vma_read,
};
bool need_lock;
- if (!folio)
- return false;
-
if (!folio_mapped(folio) || !folio_raw_mapping(folio)) {
if (folio_test_idle(folio))
- accessed = false;
+ return false;
else
- accessed = true;
- goto out;
+ return true;
}
need_lock = !folio_test_anon(folio) || folio_test_ksm(folio);
if (need_lock && !folio_trylock(folio))
- goto out;
+ return false;
rmap_walk(folio, &rwc);
if (need_lock)
folio_unlock(folio);
-out:
+ return accessed;
+}
+
+static bool damon_pa_young(unsigned long paddr, unsigned long *folio_sz)
+{
+ struct folio *folio = damon_get_folio(PHYS_PFN(paddr));
+ bool accessed;
+
+ if (!folio)
+ return false;
+
+ accessed = damon_folio_young(folio);
*folio_sz = folio_size(folio);
folio_put(folio);
return accessed;
--
2.39.2
damon_pa_mkold() receives a physical address, finds the folio covering
the address, and makes the folio as old. Split the internal logic for
checking access to the given folio, for future reuse of the logic.
Also, change the name of the rmap walker from __damon_pa_mkold() to
damon_folio_mkold_one() for more consistent naming.
Signed-off-by: SeongJae Park <[email protected]>
---
mm/damon/paddr.c | 27 ++++++++++++++++-----------
1 file changed, 16 insertions(+), 11 deletions(-)
diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
index 25c3ba2a9eaf..310b803c6277 100644
--- a/mm/damon/paddr.c
+++ b/mm/damon/paddr.c
@@ -16,8 +16,8 @@
#include "../internal.h"
#include "ops-common.h"
-static bool __damon_pa_mkold(struct folio *folio, struct vm_area_struct *vma,
- unsigned long addr, void *arg)
+static bool damon_folio_mkold_one(struct folio *folio,
+ struct vm_area_struct *vma, unsigned long addr, void *arg)
{
DEFINE_FOLIO_VMA_WALK(pvmw, folio, vma, addr, 0);
@@ -31,33 +31,38 @@ static bool __damon_pa_mkold(struct folio *folio, struct vm_area_struct *vma,
return true;
}
-static void damon_pa_mkold(unsigned long paddr)
+static void damon_folio_mkold(struct folio *folio)
{
- struct folio *folio = damon_get_folio(PHYS_PFN(paddr));
struct rmap_walk_control rwc = {
- .rmap_one = __damon_pa_mkold,
+ .rmap_one = damon_folio_mkold_one,
.anon_lock = folio_lock_anon_vma_read,
};
bool need_lock;
- if (!folio)
- return;
-
if (!folio_mapped(folio) || !folio_raw_mapping(folio)) {
folio_set_idle(folio);
- goto out;
+ return;
}
need_lock = !folio_test_anon(folio) || folio_test_ksm(folio);
if (need_lock && !folio_trylock(folio))
- goto out;
+ return;
rmap_walk(folio, &rwc);
if (need_lock)
folio_unlock(folio);
-out:
+}
+
+static void damon_pa_mkold(unsigned long paddr)
+{
+ struct folio *folio = damon_get_folio(PHYS_PFN(paddr));
+
+ if (!folio)
+ return;
+
+ damon_folio_mkold(folio);
folio_put(folio);
}
--
2.39.2
Define yet another DAMOS filter type, YOUNG. Like anon and memcg, the
type of filter will be applied to each page in the memory region, and
check if the page is accessed since the last check.
Note that this commit is only defining the type. Implementation of it
should be made on DAMON operations sets. A couple of commits for the
implementation on 'paddr' DAMON operations set will follow.
Signed-off-by: SeongJae Park <[email protected]>
---
include/linux/damon.h | 2 ++
mm/damon/sysfs-schemes.c | 1 +
2 files changed, 3 insertions(+)
diff --git a/include/linux/damon.h b/include/linux/damon.h
index 886d07294f4e..f7da65e1ac04 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -297,6 +297,7 @@ struct damos_stat {
* enum damos_filter_type - Type of memory for &struct damos_filter
* @DAMOS_FILTER_TYPE_ANON: Anonymous pages.
* @DAMOS_FILTER_TYPE_MEMCG: Specific memcg's pages.
+ * @DAMOS_FILTER_TYPE_YOUNG: Recently accessed pages.
* @DAMOS_FILTER_TYPE_ADDR: Address range.
* @DAMOS_FILTER_TYPE_TARGET: Data Access Monitoring target.
* @NR_DAMOS_FILTER_TYPES: Number of filter types.
@@ -315,6 +316,7 @@ struct damos_stat {
enum damos_filter_type {
DAMOS_FILTER_TYPE_ANON,
DAMOS_FILTER_TYPE_MEMCG,
+ DAMOS_FILTER_TYPE_YOUNG,
DAMOS_FILTER_TYPE_ADDR,
DAMOS_FILTER_TYPE_TARGET,
NR_DAMOS_FILTER_TYPES,
diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index 53a90ac678fb..bea5bc52846a 100644
--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -343,6 +343,7 @@ static struct damon_sysfs_scheme_filter *damon_sysfs_scheme_filter_alloc(void)
static const char * const damon_sysfs_scheme_filter_type_strs[] = {
"anon",
"memcg",
+ "young",
"addr",
"target",
};
--
2.39.2
DAMOS filter of type YOUNG is defined, but not yet implemented by any
DAMON operations set. Add the implementation to the DAMON operations
set for the physical address space, paddr.
Signed-off-by: SeongJae Park <[email protected]>
---
mm/damon/paddr.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
index 310b803c6277..5685ba485097 100644
--- a/mm/damon/paddr.c
+++ b/mm/damon/paddr.c
@@ -214,6 +214,11 @@ static bool __damos_pa_filter_out(struct damos_filter *filter,
matched = filter->memcg_id == mem_cgroup_id(memcg);
rcu_read_unlock();
break;
+ case DAMOS_FILTER_TYPE_YOUNG:
+ matched = damon_folio_young(folio);
+ if (matched)
+ damon_folio_mkold(folio);
+ break;
default:
break;
}
--
2.39.2
Hi SeongJae,
On Mon, 11 Mar 2024 13:45:41 -0700 SeongJae Park <[email protected]> wrote:
> Changes from RFC v1
> (https://lore.kernel.org/r/[email protected])
> - Rename __damon_pa_young() to damon_folio_young_one()
> - Mark the folio as old from the filter for the next check
>
> DAMON allows users to specify desired ranges of overhead and accuracy of
> the monitoring, and do its best effort to make most lightweight and
> accurate results. A recent discussion for tiered memory management
> support from DAMON[1] revealed that the best effort accuracy may not
> suffice in some use cases, while increasing the minimum accuracy can
> incur too high overhead. The discussion further concluded finding
> memory regions of specific access pattern via DAMON first, and then
> double checking the access of the region again in finer granularity
> could help increasing the accuracy while keeping the low overhead.
>
> Add a new type of DAMOS filter, namely YOUNG for such a case. Like anon
> and memcg, the type of filter is applied to each page of the memory
> region of DAMOS target memory region, and check if the page is accessed
> since the last check. Because this is a filter type that applied in
> page granularity, the support depends on DAMON operations set. Because
> there are expected usages of this filter for physical address space
> based DAMOS usage[1], implement the support for only DAMON operations
> set for the physical address space, paddr.
>
> [1] https://lore.kernel.org/r/[email protected]
>
>
> SeongJae Park (4):
> mm/damon/paddr: implement damon_folio_young()
> mm/damon/paddr: implement damon_folio_mkold()
> mm/damon: add DAMOS filter type YOUNG
> mm/damon/paddr: support DAMOS filter type YOUNG
I have tested your patches for evaluation of [1] and it all works fine.
Thanks very much for doing this work!
Tested-by: Honggyu Kim <[email protected]>
[1] https://lore.kernel.org/damon/[email protected]
> include/linux/damon.h | 2 ++
> mm/damon/paddr.c | 64 +++++++++++++++++++++++++---------------
> mm/damon/sysfs-schemes.c | 1 +
> 3 files changed, 43 insertions(+), 24 deletions(-)
>
>
> base-commit: 13043cde46a19e72d37965b67b74e564623f65e7
> --
> 2.39.2
>