mm/damon/reclaim: implement user-feedback driven quota auto-tuning

DAMOS supports user-feedback driven quota auto-tuning, but only DAMON
sysfs interface is using it.  Add support of the feature on DAMON_RECLAIM
by adding one more input parameter, namely 'quota_autotune_feedback', for
providing the user feedback to DAMON_RECLAIM.  It assumes the target value
of the feedback is 10,000.

Link: https://lkml.kernel.org/r/20240219194431.159606-19-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/damon/reclaim.c b/mm/damon/reclaim.c
index 66e190f..9df6b88 100644 (file)
--- a/mm/damon/reclaim.c
+++ b/mm/damon/reclaim.c
@@ -62,6 +62,21 @@ static struct damos_quota damon_reclaim_quota = {
 };
 DEFINE_DAMON_MODULES_DAMOS_QUOTAS(damon_reclaim_quota);
 
+/*
+ * User-specifiable feedback for auto-tuning of the effective quota.
+ *
+ * While keeping the caps that set by other quotas, DAMON_RECLAIM automatically
+ * increases and decreases the effective level of the quota aiming receiving this
+ * feedback of value ``10,000`` from the user.  DAMON_RECLAIM assumes the feedback
+ * value and the quota are positively proportional.  Value zero means disabling
+ * this auto-tuning feature.
+ *
+ * Disabled by default.
+ *
+ */
+static unsigned long quota_autotune_feedback __read_mostly;
+module_param(quota_autotune_feedback, ulong, 0600);
+
 static struct damos_watermarks damon_reclaim_wmarks = {
        .metric = DAMOS_WMARK_FREE_MEM_RATE,
        .interval = 5000000,    /* 5 seconds */
@@ -159,11 +174,13 @@ static void damon_reclaim_copy_quota_status(struct damos_quota *dst,
        dst->charged_from = src->charged_from;
        dst->charge_target_from = src->charge_target_from;
        dst->charge_addr_from = src->charge_addr_from;
+       dst->esz_bp = src->esz_bp;
 }
 
 static int damon_reclaim_apply_parameters(void)
 {
        struct damos *scheme, *old_scheme;
+       struct damos_quota_goal *goal;
        struct damos_filter *filter;
        int err = 0;
 
@@ -180,6 +197,17 @@ static int damon_reclaim_apply_parameters(void)
                        damon_reclaim_copy_quota_status(&scheme->quota,
                                        &old_scheme->quota);
        }
+
+       if (quota_autotune_feedback) {
+               goal = damos_new_quota_goal(DAMOS_QUOTA_USER_INPUT, 10000);
+               if (!goal) {
+                       damon_destroy_scheme(scheme);
+                       return -ENOMEM;
+               }
+               goal->current_value = quota_autotune_feedback;
+               damos_add_quota_goal(&scheme->quota, goal);
+       }
+
        if (skip_anon) {
                filter = damos_new_filter(DAMOS_FILTER_TYPE_ANON, true);
                if (!filter) {