mm/damon/sysfs: handle 'state' file inputs for every sampling interval if possible

DAMON sysfs interface need to access kdamond-touching data for some of
kdamond user commands.  It uses ->after_aggregation() kdamond callback to
safely access the data in the case.  It had to use the aggregation
interval callback because that was the only callback that users can access
complete monitoring results.

Since patch series "mm/damon: provide pseudo-moving sum based access
rate", which starts from commit 78fbfb155d20 ("mm/damon/core: define and
use a dedicated function for region access rate update"), DAMON provides
good-to-use quality moitoring results for every sampling interval.  It
aims to help users who need to quickly retrieve the monitoring results. 
When the aggregation interval is set too long and therefore waiting for
the aggregation interval can degrade user experience, or when the access
pattern is expected to be significantly changed[1] could be such cases.

However, because DAMON sysfs interface is still handling the commands per
aggregation interval, the end user cannot get the benefit.  Update DAMON
sysfs interface to handle kdamond commands for every sampling interval if
applicable.  Specifically, all kdamond data accessing commands except
'commit' command are applicable.

[1] https://lore.kernel.org/r/20240129121316.GA9706@cuiyangpei

Link: https://lkml.kernel.org/r/20240206025158.203097-1-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: xiongping1 <xiongping1@xiaomi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 18 insertions, 3 deletions

diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
index 1f891e18b4ee..678de97fcc88 100644
--- a/mm/damon/sysfs.c
+++ b/mm/damon/sysfs.c
@@ -1379,11 +1379,13 @@ static int damon_sysfs_commit_schemes_quota_goals(
  * damon_sysfs_cmd_request_callback() - DAMON callback for handling requests.
  * @c:		The DAMON context of the callback.
  * @active:	Whether @c is not deactivated due to watermarks.
+ * @after_aggr:	Whether this is called from after_aggregation() callback.
  *
  * This function is periodically called back from the kdamond thread for @c.
  * Then, it checks if there is a waiting DAMON sysfs request and handles it.
  */
-static int damon_sysfs_cmd_request_callback(struct damon_ctx *c, bool active)
+static int damon_sysfs_cmd_request_callback(struct damon_ctx *c, bool active,
+		bool after_aggregation)
 {
 	struct damon_sysfs_kdamond *kdamond;
 	bool total_bytes_only = false;
@@ -1401,6 +1403,8 @@ static int damon_sysfs_cmd_request_callback(struct damon_ctx *c, bool active)
 		err = damon_sysfs_upd_schemes_stats(kdamond);
 		break;
 	case DAMON_SYSFS_CMD_COMMIT:
+		if (!after_aggregation)
+			goto out;
 		err = damon_sysfs_commit_input(kdamond);
 		break;
 	case DAMON_SYSFS_CMD_COMMIT_SCHEMES_QUOTA_GOALS:
@@ -1418,6 +1422,7 @@ static int damon_sysfs_cmd_request_callback(struct damon_ctx *c, bool active)
 				goto keep_lock_out;
 			}
 		} else {
+			damos_sysfs_mark_finished_regions_updates(c);
 			/*
 			 * Continue regions updating if DAMON is till
 			 * active and the update for all schemes is not
@@ -1450,7 +1455,16 @@ static int damon_sysfs_after_wmarks_check(struct damon_ctx *c)
 	 * after_wmarks_check() is called back while the context is deactivated
 	 * by watermarks.
 	 */
-	return damon_sysfs_cmd_request_callback(c, false);
+	return damon_sysfs_cmd_request_callback(c, false, false);
+}
+
+static int damon_sysfs_after_sampling(struct damon_ctx *c)
+{
+	/*
+	 * after_sampling() is called back only while the context is not
+	 * deactivated by watermarks.
+	 */
+	return damon_sysfs_cmd_request_callback(c, true, false);
 }
 
 static int damon_sysfs_after_aggregation(struct damon_ctx *c)
@@ -1459,7 +1473,7 @@ static int damon_sysfs_after_aggregation(struct damon_ctx *c)
 	 * after_aggregation() is called back only while the context is not
 	 * deactivated by watermarks.
 	 */
-	return damon_sysfs_cmd_request_callback(c, true);
+	return damon_sysfs_cmd_request_callback(c, true, true);
 }
 
 static struct damon_ctx *damon_sysfs_build_ctx(
@@ -1478,6 +1492,7 @@ static struct damon_ctx *damon_sysfs_build_ctx(
 	}
 
 	ctx->callback.after_wmarks_check = damon_sysfs_after_wmarks_check;
+	ctx->callback.after_sampling = damon_sysfs_after_sampling;
 	ctx->callback.after_aggregation = damon_sysfs_after_aggregation;
 	ctx->callback.before_terminate = damon_sysfs_before_terminate;
 	return ctx;