[RFC PATCH 0/4] mm/damon: add lru-active probe filter type

[RFC PATCH 0/4] mm/damon: add lru-active probe filter type

[SJ Park]

The LRU-activeness of folios is useful information for understanding and
optimizing the system.  DAMOS ops filter therefore supports filtering
memory based on the information.  Using it, the information can be
extracted in the folio granularity.  It is precise but expensive.  DAMON
probe filter is the complementary way for getting the information in
region granularity with much cheaper cost.  DAMON filter does not
support LRU-activeness based filtering, though.  Add the support.

Define new DAMON filter type, DAMON_FILTER_TYPE_ACTIVE, on core API
(patch 1).  Add support for it on both vaddr and paddr operation set
(patch 2).  Extend DAMON filter sysfs ABI to let users configure DAMON
filters of the type using a new keyword, "active" (patch 3).  Finally,
update the DAMON design document to explain the new type (patch 4).

SJ Park (4):
  mm/damon/api: define DAMON_FILTER_TYPE_ACTIVE
  mm/damon/ops-common: implement DAMON_FILTER_TYPE_ACTIVE operation
  mm/damon/sysfs: support LRU-activeness based DAMON filter setup
  Docs/mm/damon/design: update for DAMON_FILTER_TYPE_ACTIVE

 Documentation/mm/damon/design.rst | 1 +
 include/linux/damon.h             | 2 ++
 mm/damon/ops-common.c             | 7 +++++++
 mm/damon/sysfs.c                  | 4 ++++
 4 files changed, 14 insertions(+)


base-commit: 50061821991431146db6bd16b571742c06146d30
-- 
2.47.3

[RFC PATCH 1/4] mm/damon/api: define DAMON_FILTER_TYPE_ACTIVE

[SJ Park]

Knowing which memory is on Active LRU lists is useful for understanding
and optimally operating systems.  Extend the DAMON core layer to be
ready for support of that.  For that, define a new damon_filter_type,
DAMON_FILTER_TYPE_ACTIVE.  It has no additional arguments and therefore
no additional change in the core layer is needed.  Testing if a given
memory is on an LRU list for the type of filter should be implemented in
the operation set layer.

Signed-off-by: SJ Park <sj@kernel.org>
---
 include/linux/damon.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/linux/damon.h b/include/linux/damon.h
index 1302ffb6f0bcb..858b4c6900fde 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -780,6 +780,7 @@ struct damon_prep {
  * @DAMON_FILTER_TYPE_PGIDLE_UNSET:	Pgidle is unset.
  * @DAMON_FILTER_TYPE_PGIDLE_SET:	Pgidle is set.
  * @DAMON_FILTER_TYPE_HUGEPAGE_SIZE:	Page is part of a hugepage.
+ * @DAMON_FILTER_TYPE_ACTIVE:		LRU-active pages.
  */
 enum damon_filter_type {
 	DAMON_FILTER_TYPE_ANON,
@@ -787,6 +788,7 @@ enum damon_filter_type {
 	DAMON_FILTER_TYPE_PGIDLE_UNSET,
 	DAMON_FILTER_TYPE_PGIDLE_SET,
 	DAMON_FILTER_TYPE_HUGEPAGE_SIZE,
+	DAMON_FILTER_TYPE_ACTIVE,
 };
 
 /**
-- 
2.47.3

[RFC PATCH 2/4] mm/damon/ops-common: implement DAMON_FILTER_TYPE_ACTIVE operation

[SJ Park]

Implement DAMON_FILTER_TYPE_ACTIVE operation.  Use folio_test_active()
to show if the folio of the given memory is on an active LRU list.  The
implementation is made on ops-common, so both vaddr and paddr gain the
support of the filter type.

Signed-off-by: SJ Park <sj@kernel.org>
---
 mm/damon/ops-common.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/mm/damon/ops-common.c b/mm/damon/ops-common.c
index b9571f53e538c..2216a0023154f 100644
--- a/mm/damon/ops-common.c
+++ b/mm/damon/ops-common.c
@@ -574,6 +574,13 @@ bool damon_ops_filter_match(struct damon_filter *filter, struct folio *folio)
 		matched = filter->range_min <= folio_sz &&
 			folio_sz <= filter->range_max;
 		break;
+	case DAMON_FILTER_TYPE_ACTIVE:
+		if (!folio) {
+			matched = false;
+			break;
+		}
+		matched = folio_test_active(folio);
+		break;
 	default:
 		break;
 	}
-- 
2.47.3

[RFC PATCH 3/4] mm/damon/sysfs: support LRU-activeness based DAMON filter setup

[SJ Park]

Support DAMON sysfs interface based setup of DAMON_FILTER_TYPE_ACTIVE
type DAMON filters.  For that, wire the type with a new user keyword,
"active".  Users can set up the new type of filter using the existing
DAMON filter setup interface with the new keyword.

Signed-off-by: SJ Park <sj@kernel.org>
---
 mm/damon/sysfs.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
index 70a4b64fb8ea9..779c98205a94b 100644
--- a/mm/damon/sysfs.c
+++ b/mm/damon/sysfs.c
@@ -1011,6 +1011,10 @@ damon_sysfs_filter_type_names[] = {
 		.type = DAMON_FILTER_TYPE_HUGEPAGE_SIZE,
 		.name = "hugepage_size",
 	},
+	{
+		.type = DAMON_FILTER_TYPE_ACTIVE,
+		.name = "active",
+	},
 };
 
 static ssize_t type_show(struct kobject *kobj,
-- 
2.47.3

[RFC PATCH 4/4] Docs/mm/damon/design: update for DAMON_FILTER_TYPE_ACTIVE

[SJ Park]

Update DAMON design document for the newly added LRU-activeness DAMON
filter type.

Signed-off-by: SJ Park <sj@kernel.org>
---
 Documentation/mm/damon/design.rst | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Documentation/mm/damon/design.rst b/Documentation/mm/damon/design.rst
index 8440c4954090e..b676be6971589 100644
--- a/Documentation/mm/damon/design.rst
+++ b/Documentation/mm/damon/design.rst
@@ -302,6 +302,7 @@ filter types.  Currently below filter types are supported.
 - ``pgidle_set``: Matches if the page for the memory is marked as access-idle.
 - ``hugepage_size``: Matches if the page for the memory is a part of a hugepage
   of a given size range.
+- ``active``: Same to that for DAMOS filters.
 
 If such probes are registered, DAMON executes the probes for each region's
 sampling memory when it does the access :ref:`sampling
-- 
2.47.3