[RFC PATCH v2 04/10] mm/damon/sysfs-schemes: implement quotas->goal_tuner file

SeongJae Park
2026-03-04T04:41:28Z

Add a new DAMON sysfs interface file, namely 'goal_tuner' under the
DAMOS quotas directory. It is connected to the damos_quota->goal_tuner
field. Users can therefore select their favorite goal-based quotas
tuning algorithm by writing the name of the tuner to the file. Reading
the file returns the name of the currently selected tuner.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
mm/damon/sysfs-schemes.c | 58 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 58 insertions(+)

diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index 3a0782e576fab..5186966dafb35 100644
--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -1488,6 +1488,7 @@ struct damon_sysfs_quotas {
unsigned long sz;
unsigned long reset_interval_ms;
unsigned long effective_sz; /* Effective size quota in bytes */
+ enum damos_quota_goal_tuner goal_tuner;
};

static struct damon_sysfs_quotas *damon_sysfs_quotas_alloc(void)
@@ -1610,6 +1611,58 @@ static ssize_t effective_bytes_show(struct kobject *kobj,
return sysfs_emit(buf, "%lu\n", quotas->effective_sz);
}

+struct damos_sysfs_qgoal_tuner_name {
+ enum damos_quota_goal_tuner tuner;
+ char *name;
+};
+
+static struct damos_sysfs_qgoal_tuner_name damos_sysfs_qgoal_tuner_names[] = {
+ {
+ .tuner = DAMOS_QUOTA_GOAL_TUNER_CONSIST,
+ .name = "consist",
+ },
+ {
+ .tuner = DAMOS_QUOTA_GOAL_TUNER_TEMPORAL,
+ .name = "temporal",
+ },
+};
+
+static ssize_t goal_tuner_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ struct damon_sysfs_quotas *quotas = container_of(kobj,
+ struct damon_sysfs_quotas, kobj);
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(damos_sysfs_qgoal_tuner_names); i++) {
+ struct damos_sysfs_qgoal_tuner_name *tuner_name;
+
+ tuner_name = &damos_sysfs_qgoal_tuner_names[i];
+ if (tuner_name->tuner == quotas->goal_tuner)
+ return sysfs_emit(buf, "%s\n", tuner_name->name);
+ }
+ return -EINVAL;
+}
+
+static ssize_t goal_tuner_store(struct kobject *kobj,
+ struct kobj_attribute *attr, const char *buf, size_t count)
+{
+ struct damon_sysfs_quotas *quotas = container_of(kobj,
+ struct damon_sysfs_quotas, kobj);
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(damos_sysfs_qgoal_tuner_names); i++) {
+ struct damos_sysfs_qgoal_tuner_name *tuner_name;
+
+ tuner_name = &damos_sysfs_qgoal_tuner_names[i];
+ if (sysfs_streq(buf, tuner_name->name)) {
+ quotas->goal_tuner = tuner_name->tuner;
+ return count;
+ }
+ }
+ return -EINVAL;
+}
+
static void damon_sysfs_quotas_release(struct kobject *kobj)
{
kfree(container_of(kobj, struct damon_sysfs_quotas, kobj));
@@ -1627,11 +1680,15 @@ static struct kobj_attribute damon_sysfs_quotas_reset_interval_ms_attr =
static struct kobj_attribute damon_sysfs_quotas_effective_bytes_attr =
__ATTR_RO_MODE(effective_bytes, 0400);

+static struct kobj_attribute damon_sysfs_quotas_goal_tuner_attr =
+ __ATTR_RW_MODE(goal_tuner, 0600);
+
static struct attribute *damon_sysfs_quotas_attrs[] = {
&damon_sysfs_quotas_ms_attr.attr,
&damon_sysfs_quotas_sz_attr.attr,
&damon_sysfs_quotas_reset_interval_ms_attr.attr,
&damon_sysfs_quotas_effective_bytes_attr.attr,
+ &damon_sysfs_quotas_goal_tuner_attr.attr,
NULL,
};
ATTRIBUTE_GROUPS(damon_sysfs_quotas);
@@ -2718,6 +2775,7 @@ static struct damos *damon_sysfs_mk_scheme(
.weight_sz = sysfs_weights->sz,
.weight_nr_accesses = sysfs_weights->nr_accesses,
.weight_age = sysfs_weights->age,
+ .goal_tuner = sysfs_quotas->goal_tuner,
};
struct damos_watermarks wmarks = {
.metric = sysfs_wmarks->metric,
--
2.47.3