mm/damon/schemes: account how many times quota limit has exceeded

If the time/space quotas of a given DAMON-based operation scheme is too small, the scheme could show unexpectedly slow progress. However, there is no good way to notice the case in runtime. This commit extends the DAMOS stat to provide how many times the quota limits exceeded so that the users can easily notice the case and tune the scheme. Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: SeongJae Park <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
LoveHeat · Jan 15, 2022 · 6268eac · 6268eac
1 parent 0e92c2e
commit 6268eac
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diff --git a/include/linux/damon.h b/include/linux/damon.h
@@ -198,12 +198,14 @@ struct damos_watermarks {
  * @sz_tried:	Total size of regions that the scheme is tried to be applied.
  * @nr_applied:	Total number of regions that the scheme is applied.
  * @sz_applied:	Total size of regions that the scheme is applied.
+ * @qt_exceeds: Total number of times the quota of the scheme has exceeded.
  */
 struct damos_stat {
 	unsigned long nr_tried;
 	unsigned long sz_tried;
 	unsigned long nr_applied;
 	unsigned long sz_applied;
+	unsigned long qt_exceeds;
 };
 
 /**

diff --git a/mm/damon/core.c b/mm/damon/core.c
@@ -693,6 +693,8 @@ static void kdamond_apply_schemes(struct damon_ctx *c)
 		if (time_after_eq(jiffies, quota->charged_from +
 					msecs_to_jiffies(
 						quota->reset_interval))) {
+			if (quota->esz && quota->charged_sz >= quota->esz)
+				s->stat.qt_exceeds++;
 			quota->total_charged_sz += quota->charged_sz;
 			quota->charged_from = jiffies;
 			quota->charged_sz = 0;