[RFC PATCH 0/6] mm/damon: introduce probe_hits_wsum DAMOS core filter

[RFC PATCH 0/6] mm/damon: introduce probe_hits_wsum DAMOS core filter

[SJ Park]

DAMON can do flexible data attributes monitoring.  The classical data
access monitoring can also be done using the attributes monitoring.  The
access event is just one of the data attributes that DAMON supports.
Users do monitoring to make some actions based on it.  DAMOS is a
feature for automating that.  However, DAMOS cannot utilize the data
attributes monitoring results.  It is still Data "Access"
Monitoring-based Operation Schemes.  It requires users to set the target
"access" pattern.

DAMOS core filter is effectively the same as the target access pattern.
It is just a more generalized and flexible way of describing the
operation action target region.  Introduce a new DAMOS core filter type,
probe_hits_wsum.  It specifies the filter target based on a range of the
probe hits weighted sum.  Using this, users can apply DAMOS actions to
regions of specific data attributes pattern.

Note that the classic target access pattern still works.  Hence the
target nr_accesses range should still be properly configured.  The new
filter would be used in only data attributes-only mode.  In the mode,
classic access monitoring is just turned off, and therefore nr_accesses
of regions are always zero.  Users could simply set the target
nr_accesses range to include the zero nr_Accesses regions.

Patches Sequence
================

Patch 1 updates the DAMON kernel API for the new filter type.  Patch 2
implements the filter type in the core layer.  Patch 3 refactor DAMON
sysfs interface internal data structure for efficient reuse of data
structure for the probe hits weighted sum range user inputs.  Patch 4
updates DAMON sysfs interface to support the new filter type.  Patches 5
and 6 update design and usage documents for the new filter type,
respectively.

SJ Park (6):
  mm/damon/api: introduce DAMOS_FILTER_TYPE_PROBE_HITS_WSUM
  mm/damon/core: support probe_hits_wsum damos core filter
  mm/damon/sysfs-schemes: rename sysfs_filter->sz_range to
    range_{min,max}
  mm/damon/sysfs-schemes: setup range_{min,max} for probe_hits_wsum
    filter
  Docs/mm/damon/design: update for probe_hits_wsum DAMOS core filter
  Docs/admin-guide/mm/damon/usage: update for probe_hits_wsum DAMOS
    filter

 Documentation/admin-guide/mm/damon/usage.rst |  4 +++
 Documentation/mm/damon/design.rst            |  3 ++
 include/linux/damon.h                        |  8 ++++++
 mm/damon/core.c                              | 12 +++++++-
 mm/damon/sysfs-schemes.c                     | 30 ++++++++++++++------
 5 files changed, 48 insertions(+), 9 deletions(-)


base-commit: 787c63ba44ce65021966f55673e27d778c8d9c68
-- 
2.47.3

[RFC PATCH 1/6] mm/damon/api: introduce DAMOS_FILTER_TYPE_PROBE_HITS_WSUM

[SJ Park]

Update DAMON kernel API to introduce new DAMOS core filter type,
PROBE_HITS_WSUM.  It will allow API callers to describe the DAMOS action
target regions based on their probe_hits weighted sum.  For describing
the filtering target weighted sum range, add two type-dependent union
fields to damos_filter.

Signed-off-by: SJ Park <sj@kernel.org>
---
 include/linux/damon.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/include/linux/damon.h b/include/linux/damon.h
index 871d26adf6ae5..59d57131d8327 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -399,6 +399,7 @@ struct damos_stat {
  * @DAMOS_FILTER_TYPE_UNMAPPED:	Unmapped pages.
  * @DAMOS_FILTER_TYPE_ADDR:	Address range.
  * @DAMOS_FILTER_TYPE_TARGET:	Data Access Monitoring target.
+ * @DAMOS_FILTER_TYPE_PROBE_HITS_WSUM:	probe_hits weighted sum range.
  * @NR_DAMOS_FILTER_TYPES:	Number of filter types.
  *
  * All types except &DAMOS_FILTER_TYPE_ADDR and &DAMOS_FILTER_TYPE_TARGET
@@ -420,6 +421,7 @@ enum damos_filter_type {
 	DAMOS_FILTER_TYPE_UNMAPPED,
 	DAMOS_FILTER_TYPE_ADDR,
 	DAMOS_FILTER_TYPE_TARGET,
+	DAMOS_FILTER_TYPE_PROBE_HITS_WSUM,
 	NR_DAMOS_FILTER_TYPES,
 };
 
@@ -434,6 +436,8 @@ enum damos_filter_type {
  *		&damon_ctx->adaptive_targets if @type is
  *		DAMOS_FILTER_TYPE_TARGET.
  * @sz_range:	Size range if @type is DAMOS_FILTER_TYPE_HUGEPAGE_SIZE.
+ * @range_min:	Minimum value of range arguments.
+ * @range_mx:	Maximum value of range arguments.
  *
  * Before applying the &damos->action to a memory region, DAMOS checks if each
  * byte of the region matches to this given condition and avoid applying the
@@ -450,6 +454,10 @@ struct damos_filter {
 		struct damon_addr_range addr_range;
 		int target_idx;
 		struct damon_size_range sz_range;
+		struct {
+			unsigned long range_min;
+			unsigned long range_max;
+		};
 	};
 /* private: */
 	/* List head for siblings. */
-- 
2.47.3

[RFC PATCH 2/6] mm/damon/core: support probe_hits_wsum damos core filter

[SJ Park]

Implement probe_hits_wsum DAMOS core filter support in the core layer.
Make three small changes for the support.  First, update
damos_filter_for_ops() to treat probe_hits_wsum filter as core filter.
Second, Update destination damos_filter->range_{min,max} for
probe_hits_wsum type damos filter commits.  Third, extend
damos_filter_match() to handle probe_hits_wsum type filter. Calculate
the weighted sum of the given region and compare it with the given
filter's target weighted sum range.

Signed-off-by: SJ Park <sj@kernel.org>
---
 mm/damon/core.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/mm/damon/core.c b/mm/damon/core.c
index 1752afede01e2..5b976162c5eed 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -654,6 +654,7 @@ bool damos_filter_for_ops(enum damos_filter_type type)
 	switch (type) {
 	case DAMOS_FILTER_TYPE_ADDR:
 	case DAMOS_FILTER_TYPE_TARGET:
+	case DAMOS_FILTER_TYPE_PROBE_HITS_WSUM:
 		return false;
 	default:
 		break;
@@ -1328,6 +1329,10 @@ static void damos_commit_filter_arg(
 	case DAMOS_FILTER_TYPE_HUGEPAGE_SIZE:
 		dst->sz_range = src->sz_range;
 		break;
+	case DAMOS_FILTER_TYPE_PROBE_HITS_WSUM:
+		dst->range_min = src->range_min;
+		dst->range_max = src->range_max;
+		break;
 	default:
 		break;
 	}
@@ -2506,7 +2511,7 @@ static bool damos_filter_match(struct damon_ctx *ctx, struct damon_target *t,
 	bool matched = false;
 	struct damon_target *ti;
 	int target_idx = 0;
-	unsigned long start, end;
+	unsigned long start, end, wsum;
 
 	switch (filter->type) {
 	case DAMOS_FILTER_TYPE_TARGET:
@@ -2541,6 +2546,11 @@ static bool damos_filter_match(struct damon_ctx *ctx, struct damon_target *t,
 		damon_split_region_at(t, r, end - r->ar.start);
 		matched = true;
 		break;
+	case DAMOS_FILTER_TYPE_PROBE_HITS_WSUM:
+		wsum = damon_probe_hits_wsum(r, false, ctx);
+		matched = filter->range_min <= wsum &&
+			wsum <= filter->range_max;
+		break;
 	default:
 		return false;
 	}
-- 
2.47.3

[RFC PATCH 3/6] mm/damon/sysfs-schemes: rename sysfs_filter->sz_range to range_{min,max}

[SJ Park]

DAMON sysfs interface provides 'min' and 'max' files under the DAMOS
filter directory.  The purpose is setting the general range arguments
for hugepage_size like filters that require range arguments.  So far,
hugepage_size was the only filter using it.  Hence sz_range field of
damon_sysfs_scheme_filter struct was connected to the files.

In future, we could add a new filter that can reuse the 'min' and 'max'
files.  And the filter might use a range of a type that is not size. For
example, probe_hits weighted sum.  In this case, simply reusing the
sz_range field would make it a little confusing.  Rename sz_range to
range_{min,max} to avoid such confusion.

Signed-off-by: SJ Park <sj@kernel.org>
---
 mm/damon/sysfs-schemes.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index d9b81d7b5910e..4d9147d2a269e 100644
--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -534,7 +534,8 @@ struct damon_sysfs_scheme_filter {
 	bool allow;
 	char *memcg_path;
 	struct damon_addr_range addr_range;
-	struct damon_size_range sz_range;
+	unsigned long range_min;
+	unsigned long range_max;
 	int target_idx;
 };
 
@@ -588,6 +589,7 @@ damos_sysfs_filter_type_names[] = {
 		.type = DAMOS_FILTER_TYPE_TARGET,
 		.name = "target",
 	},
+
 };
 
 static ssize_t type_show(struct kobject *kobj,
@@ -778,7 +780,7 @@ static ssize_t min_show(struct kobject *kobj,
 	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
 			struct damon_sysfs_scheme_filter, kobj);
 
-	return sysfs_emit(buf, "%lu\n", filter->sz_range.min);
+	return sysfs_emit(buf, "%lu\n", filter->range_min);
 }
 
 static ssize_t min_store(struct kobject *kobj,
@@ -786,7 +788,7 @@ static ssize_t min_store(struct kobject *kobj,
 {
 	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
 			struct damon_sysfs_scheme_filter, kobj);
-	int err = kstrtoul(buf, 0, &filter->sz_range.min);
+	int err = kstrtoul(buf, 0, &filter->range_min);
 
 	return err ? err : count;
 }
@@ -797,7 +799,7 @@ static ssize_t max_show(struct kobject *kobj,
 	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
 			struct damon_sysfs_scheme_filter, kobj);
 
-	return sysfs_emit(buf, "%lu\n", filter->sz_range.max);
+	return sysfs_emit(buf, "%lu\n", filter->range_max);
 }
 
 static ssize_t max_store(struct kobject *kobj,
@@ -805,7 +807,7 @@ static ssize_t max_store(struct kobject *kobj,
 {
 	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
 			struct damon_sysfs_scheme_filter, kobj);
-	int err = kstrtoul(buf, 0, &filter->sz_range.max);
+	int err = kstrtoul(buf, 0, &filter->range_max);
 
 	return err ? err : count;
 }
@@ -2835,12 +2837,13 @@ static int damon_sysfs_add_scheme_filters(struct damos *scheme,
 		} else if (filter->type == DAMOS_FILTER_TYPE_TARGET) {
 			filter->target_idx = sysfs_filter->target_idx;
 		} else if (filter->type == DAMOS_FILTER_TYPE_HUGEPAGE_SIZE) {
-			if (sysfs_filter->sz_range.min >
-					sysfs_filter->sz_range.max) {
+			if (sysfs_filter->range_min >
+					sysfs_filter->range_max) {
 				damos_destroy_filter(filter);
 				return -EINVAL;
 			}
-			filter->sz_range = sysfs_filter->sz_range;
+			filter->sz_range.min = sysfs_filter->range_min;
+			filter->sz_range.max = sysfs_filter->range_max;
 		}
 
 		damos_add_filter(scheme, filter);
-- 
2.47.3

[RFC PATCH 4/6] mm/damon/sysfs-schemes: setup range_{min,max} for probe_hits_wsum filter

[SJ Park]

Extend DAMON sysfs interface to support probe_hits_wsum input.  Also
update sysfs input based scheme build logic to setup the min/max probe
hits weighted sum range as user provided.

Signed-off-by: SJ Park <sj@kernel.org>
---
 mm/damon/sysfs-schemes.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index 4d9147d2a269e..e297a20c0af03 100644
--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -589,7 +589,10 @@ damos_sysfs_filter_type_names[] = {
 		.type = DAMOS_FILTER_TYPE_TARGET,
 		.name = "target",
 	},
-
+	{
+		.type = DAMOS_FILTER_TYPE_PROBE_HITS_WSUM,
+		.name = "probe_hits_wsum",
+	},
 };
 
 static ssize_t type_show(struct kobject *kobj,
@@ -2844,6 +2847,14 @@ static int damon_sysfs_add_scheme_filters(struct damos *scheme,
 			}
 			filter->sz_range.min = sysfs_filter->range_min;
 			filter->sz_range.max = sysfs_filter->range_max;
+		} else if (filter->type == DAMOS_FILTER_TYPE_PROBE_HITS_WSUM) {
+			if (sysfs_filter->range_min >
+					sysfs_filter->range_max) {
+				damos_destroy_filter(filter);
+				return -EINVAL;
+			}
+			filter->sz_range.min = sysfs_filter->range_min;
+			filter->sz_range.max = sysfs_filter->range_max;
 		}
 
 		damos_add_filter(scheme, filter);
-- 
2.47.3

[RFC PATCH 5/6] Docs/mm/damon/design: update for probe_hits_wsum DAMOS core filter

[SJ Park]

Update DAMON design document for the newly added probe hits weighted sum
based DAMOS core filter type.

Signed-off-by: SJ Park <sj@kernel.org>
---
 Documentation/mm/damon/design.rst | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Documentation/mm/damon/design.rst b/Documentation/mm/damon/design.rst
index aac84de261aa8..8e980dde362de 100644
--- a/Documentation/mm/damon/design.rst
+++ b/Documentation/mm/damon/design.rst
@@ -822,6 +822,9 @@ Below ``type`` of filters are currently supported.
         - Applied to pages that belonging to a given address range.
     - target
         - Applied to pages that belonging to a given DAMON monitoring target.
+    - probe_hits_wsum
+        - Matches to monitoring regions having a given range of :ref:`probe
+          hits weighted sum <damon_design_attrs_only_monitoring>` value.
 - Operations layer handled, supported by only ``paddr`` operations set.
     - anon
         - Applied to pages that containing data that not stored in files.
-- 
2.47.3

[RFC PATCH 6/6] Docs/admin-guide/mm/damon/usage: update for probe_hits_wsum DAMOS filter

[SJ Park]

Update DAMON usage document for the newly added probe hits weighted sum
based DAMOS core filter type.

Signed-off-by: SJ Park <sj@kernel.org>
---
 Documentation/admin-guide/mm/damon/usage.rst | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Documentation/admin-guide/mm/damon/usage.rst b/Documentation/admin-guide/mm/damon/usage.rst
index 023c6334024f8..d3e37400367bd 100644
--- a/Documentation/admin-guide/mm/damon/usage.rst
+++ b/Documentation/admin-guide/mm/damon/usage.rst
@@ -551,6 +551,10 @@ and ``damon_target_idx``.  To ``type`` file, you can write the type of the
 filter.  Refer to :ref:`the design doc <damon_design_damos_filters>` for
 available type names, their meaning and on what layer those are handled.
 
+For ``probe_hits_wsum`` type, you can specify the minimum and maximum probe
+hits weighted sum value for the filter to ``min`` and ``max`` files,
+respectively.
+
 For ``memcg`` type, you can specify the memory cgroup of the interest by
 writing the path of the memory cgroup from the cgroups mount point to
 ``memcg_path`` file.  For ``addr`` type, you can specify the start and end
-- 
2.47.3