mm/damon/sysfs-schemes: commit damos quota goals user input to DAMOS

Make DAMON sysfs interface to read the user inputs for DAMOS quota goals
and pass those to DAMOS, so that the users can use the quota auto-tuning
feature.  It uses the DAMON sysfs interface's user input commit mechanism,
which applies all user inputs for initial starting of DAMON and online
input updates, which can be done by writing 'on' and 'commit' to the
kdamond's 'state' file, respectively.  In other words, the user should
periodically write appropriate value to 'current_value' files and 'commit'
command to the 'state' file.  'target_value' files could also be similarly
updated at any time.

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.

Link: https://lkml.kernel.org/r/20231130023652.50284-4-sj@kernel.orgSigned-off-by: SeongJae Park <sj@kernel.org>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: David Gow <davidgow@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/damon/sysfs-schemes.c

@@ -1868,6 +1868,34 @@ 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)
 {
@@ -1905,6 +1933,8 @@ 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)
@@ -1945,6 +1975,8 @@ 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;