[RFC PATCH 3/8] mm/damon/sysfs-schemes: commit damos quota goals user input to DAMOS quota auto-tuning

[SeongJae Park <sj@kernel.org>]

Make DAMON sysfs interface to read the DAMOS quota goals user input and
pass it to DAMOS so that the input can be used for the quota
auto-tuning.  The committing is made for initial starting of DAMON, and
online input updates that can be done via 'commit' input to the
kdamond's 'state' file.  That is, the user should periodically write
'current_value' files under goal directories and write 'commit' command
to the 'state' file.

Note that the interface is supporting multiple goals while the core
logic supports only one goal.  DAMON sysfs interface passes only best
feedback among the given inputs, to avoid making DAMOS too aggressive.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/sysfs-schemes.c | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index d3b57348f07b..10d8678e48ea 100644
--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -1860,6 +1860,34 @@ static int damon_sysfs_set_scheme_filters(struct damos *scheme,
 	return 0;
 }
 
+static unsigned long damos_sysfs_get_quota_score(void *arg)
+{
+	return (unsigned long)arg;
+}
+
+static void damos_sysfs_set_quota_score(
+		struct damos_sysfs_quota_goals *sysfs_goals,
+		struct damos_quota *quota)
+{
+	struct damos_sysfs_quota_goal *sysfs_goal;
+	int i;
+
+	quota->get_score = NULL;
+	quota->get_score_arg = (void *)0;
+	for (i = 0; i < sysfs_goals->nr; i++) {
+		sysfs_goal = sysfs_goals->goals_arr[i];
+		if (!sysfs_goal->target_value)
+			continue;
+
+		/* Higher score makes scheme less aggressive */
+		quota->get_score_arg = (void *)max(
+				(unsigned long)quota->get_score_arg,
+				sysfs_goal->current_value * 10000 /
+				sysfs_goal->target_value);
+		quota->get_score = damos_sysfs_get_quota_score;
+	}
+}
+
 static struct damos *damon_sysfs_mk_scheme(
 		struct damon_sysfs_scheme *sysfs_scheme)
 {
@@ -1897,6 +1925,8 @@ static struct damos *damon_sysfs_mk_scheme(
 		.low = sysfs_wmarks->low,
 	};
 
+	damos_sysfs_set_quota_score(sysfs_quotas->goals, &quota);
+
 	scheme = damon_new_scheme(&pattern, sysfs_scheme->action,
 			sysfs_scheme->apply_interval_us, &quota, &wmarks);
 	if (!scheme)
@@ -1937,6 +1967,8 @@ static void damon_sysfs_update_scheme(struct damos *scheme,
 	scheme->quota.weight_nr_accesses = sysfs_weights->nr_accesses;
 	scheme->quota.weight_age = sysfs_weights->age;
 
+	damos_sysfs_set_quota_score(sysfs_quotas->goals, &scheme->quota);
+
 	scheme->wmarks.metric = sysfs_wmarks->metric;
 	scheme->wmarks.interval = sysfs_wmarks->interval_us;
 	scheme->wmarks.high = sysfs_wmarks->high;
-- 
2.34.1