[PATCH 1/9] mm/damon/core: introduce damos->ops_filters

[SeongJae Park]

DAMOS filters can be categorized into two groups depending on which
layer they are handled, namely core layer and ops layer.  The groups are
important because the filtering behavior depends on evaluation sequence
of filters, and core layer-handled filters are evaluated before
operations layer-handled ones.

The behavior is clearly documented, but the implementation is bit
inefficient and complicated.  All filters are maintained in a single
list (damos->filters) in mix.  Filters evaluation logics in core layer
and operations layer iterates all the filters on the list, while
skipping filters that should be not handled by the layer of the logic.
It is inefficient.  Making future extensions having differentiations for
filters of different handling layers will also be complicated.

Add a new list that will be used for having all operations layer-handled
DAMOS filters to DAMOS scheme data structure.  Also add the support of
its initialization and basic traversal functions.

Signed-off-by: SeongJae Park <sj@xxxxxxxxxx>
---
 include/linux/damon.h | 8 ++++++++
 mm/damon/core.c       | 1 +
 2 files changed, 9 insertions(+)

diff --git a/include/linux/damon.h b/include/linux/damon.h
index b3e2c793c1f4..7f76e2e99f37 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -448,6 +448,7 @@ struct damos_access_pattern {
  * @wmarks:		Watermarks for automated (in)activation of this scheme.
  * @target_nid:		Destination node if @action is "migrate_{hot,cold}".
  * @filters:		Additional set of &struct damos_filter for &action.
+ * @ops_filters:	ops layer handling &struct damos_filter objects list.
  * @last_applied:	Last @action applied ops-managing entity.
  * @stat:		Statistics of this scheme.
  * @list:		List head for siblings.
@@ -508,6 +509,7 @@ struct damos {
 		int target_nid;
 	};
 	struct list_head filters;
+	struct list_head ops_filters;
 	void *last_applied;
 	struct damos_stat stat;
 	struct list_head list;
@@ -858,6 +860,12 @@ static inline unsigned long damon_sz_region(struct damon_region *r)
 #define damos_for_each_filter_safe(f, next, scheme) \
 	list_for_each_entry_safe(f, next, &(scheme)->filters, list)
 
+#define damos_for_each_ops_filter(f, scheme) \
+	list_for_each_entry(f, &(scheme)->ops_filters, list)
+
+#define damos_for_each_ops_filter_safe(f, next, scheme) \
+	list_for_each_entry_safe(f, next, &(scheme)->ops_filters, list)
+
 #ifdef CONFIG_DAMON
 
 struct damon_region *damon_new_region(unsigned long start, unsigned long end);
diff --git a/mm/damon/core.c b/mm/damon/core.c
index 9d37d3664030..5415b7603d01 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -375,6 +375,7 @@ struct damos *damon_new_scheme(struct damos_access_pattern *pattern,
 	scheme->next_apply_sis = 0;
 	scheme->walk_completed = false;
 	INIT_LIST_HEAD(&scheme->filters);
+	INIT_LIST_HEAD(&scheme->ops_filters);
 	scheme->stat = (struct damos_stat){};
 	INIT_LIST_HEAD(&scheme->list);
 
-- 
2.39.5