[RFC PATCH v3 35/37] mm/damon/core: support write access sample filter

SeongJae Park
2025-12-08T06:30:43Z

Now page fault events based access reports contain information about if
the access was for a read or a write. Doing sampling results filtering
based on the information can be useful. Introduce a new type of damon
sample filter for that.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
include/linux/damon.h | 9 ++++++---
mm/damon/core.c | 5 +++++
2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/include/linux/damon.h b/include/linux/damon.h
index 9299fc91ba27..f9fd26f7eab8 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -790,12 +790,14 @@ struct damon_primitives_enabled {
*
* @DAMON_FILTER_TYPE_CPUMASK: Filter by access-generated CPUs.
* @DAMON_FILTER_TYPE_THREADS: Filter by access-generated threads.
+ * @DAMON_FILTER_TYPE_WRITE: Filter by whether the access was for writing.
*
* Read &struct damon_sample_control for more details.
*/
enum damon_sample_filter_type {
DAMON_FILTER_TYPE_CPUMASK,
DAMON_FILTER_TYPE_THREADS,
+ DAMON_FILTER_TYPE_WRITE,
};

/**
@@ -836,9 +838,10 @@ struct damon_sample_filter {
* that to make higher access pattern picture. It can use multiple sampling
* primitives including page table accessed bits and page fault events. It can
* also filter in/out specific types of sampled access events to monitor
- * accesses of specific types, such as access-generated CPUs and threads. This
- * struct is for controlling what sampling primitives to use (enable), and what
- * sampled access events should be filtered in/out.
+ * accesses of specific types, such as access-generated CPUs, threads, and
+ * whether it was for read or writes. This struct is for controlling what
+ * sampling primitives to use (enable), and what sampled access events should
+ * be filtered in/out.
*/
struct damon_sample_control {
struct damon_primitives_enabled primitives_enabled;
diff --git a/mm/damon/core.c b/mm/damon/core.c
index e2fd17b83a92..5f29e4dee267 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -1336,6 +1336,8 @@ static int damon_commit_sample_filter_arg(struct damon_sample_filter *dst,
src->nr_tids);
dst->nr_tids = src->nr_tids;
break;
+ case DAMON_FILTER_TYPE_WRITE:
+ break;
default:
break;
}
@@ -2912,6 +2914,9 @@ static bool damon_sample_filter_matching(struct damon_access_report *report,
break;
}
break;
+ case DAMON_FILTER_TYPE_WRITE:
+ matched = report->is_write;
+ break;
default:
break;
}
--
2.47.3