[PATCH v6 05/14] mm/damon: Implement callbacks

[SeongJae Park <sjpark@amazon.com>]

From: SeongJae Park <sjpark@amazon.de>

This commit implements callbacks for DAMON.  Using this, DAMON users can
install their callbacks for each step of the access monitoring so that
they can do something interesting with the monitored access pattrns
online.  For example, callbacks can report the monitored patterns to
users or do some access pattern based memory management such as
proactive reclamations or access pattern based THP promotions/demotions
decision makings.

Signed-off-by: SeongJae Park <sjpark@amazon.de>
---
 mm/damon.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/mm/damon.c b/mm/damon.c
index 6a17408e83c2..554720778e8a 100644
--- a/mm/damon.c
+++ b/mm/damon.c
@@ -83,6 +83,10 @@ struct damon_ctx {
 	struct rnd_state rndseed;
 
 	struct list_head tasks_list;	/* 'damon_task' objects */
+
+	/* callbacks */
+	void (*sample_cb)(struct damon_ctx *context);
+	void (*aggregate_cb)(struct damon_ctx *context);
 };
 
 /* Get a random number in [l, r) */
@@ -814,9 +818,13 @@ static int kdamond_fn(void *data)
 			}
 			mmput(mm);
 		}
+		if (ctx->sample_cb)
+			ctx->sample_cb(ctx);
 
 		if (kdamond_aggregate_interval_passed(ctx)) {
 			kdamond_merge_regions(ctx, max_nr_accesses / 10);
+			if (ctx->aggregate_cb)
+				ctx->aggregate_cb(ctx);
 			kdamond_flush_aggregated(ctx);
 			kdamond_split_regions(ctx);
 		}
-- 
2.17.1