[RFC PATCH v3 15/37] mm/damon: implement sample filter data structure for cpus-only monitoring

[SeongJae Park <sj@kernel.org>]

Access information that is reported via damon_report_access() can inform
DAMON not only whether there was an access, but also additional things
such as the access-generated CPU.  By filtering in/out specific types of
the reported access based on such additional information, DAMON can
support more fine-tuned monitoring, such as per-CPUs access monitoring.
Implement a core API data structure for controlling such filtering.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 include/linux/damon.h | 39 +++++++++++++++++++++++++++++++++++++--
 1 file changed, 37 insertions(+), 2 deletions(-)

diff --git a/include/linux/damon.h b/include/linux/damon.h
index e23a10ba7c92..78be584ce5dd 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -781,18 +781,53 @@ struct damon_primitives_enabled {
 	bool page_fault;
 };
 
+/**
+ * enum damon_sample_filter_type - Type of &struct damon_sample_filter.
+ *
+ * @DAMON_FILTER_TYPE_CPUMASK:	Filter by access-generated CPUs.
+ *
+ * Read &struct damon_sample_control for more details.
+ */
+enum damon_sample_filter_type {
+	DAMON_FILTER_TYPE_CPUMASK,
+};
+
+/**
+ * struct damon_sample_filter - &struct damon_access_report filter.
+ *
+ * @type:	The type of this filter.
+ * @matching:	Whether it is for condition-matching reports.
+ * @allow:	Whether to include or excludie the @matching reports.
+ * @cpumask:	Access-generated CPUs if @type is DAMON_FILTER_TYPE_CPUMASK.
+ * @list:	List head for siblings.
+ *
+ * Read &struct damon_sample_control for more details.
+ */
+struct damon_sample_filter {
+	enum damon_sample_filter_type type;
+	bool matching;
+	bool allow;
+	cpumask_t cpumask;
+	struct list_head list;
+};
+
 /**
  * struct damon_sample_control - Low level access check sampling rules.
  *
  * @primitives_enabled:	Enablement of access check primitives.
+ * @sample_filters:	List of access check sample filters.
  *
  * DAMON collect low level access information using sampling, and aggregate
  * that to make higher access pattern picture.  It can use multiple sampling
- * primitives including page table accessed bits and page fault events.  This
- * struct is for controlling what sampling primitives to use (enable).
+ * 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.  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;
+	struct list_head sample_filters;
 };
 
 /**
-- 
2.47.3