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mm/damon/ops-common: use nr_accesses moving sum for quota score

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Since commit 42f994b714 ("mm/damon/core: implement scheme-specific apply
interval"), DAMOS scheme can be applied at any time.  At that time,
nr_accesses may not be fully aggregated.  But the quota prioritization
score is calculated using the not fully aggregated count.  As a result,
the performance of DAMOS could be degraded.  Fix by using
damon_nr_accesses_mvsum() instead.

The user impact of the issue is suboptimum DAMOS performance under certain
setups.  Nonetheless, the bug was there from the beginning of the setup
availability.  In other words, the suboptimum performance is the baseline
of the setup and hence it didn't cause regression.  Also the extent of the
suboptimality was not big enough to be found from users and testers. 
Still, this is a clear bug that is better to be fixed, and can be easily
fixed.

Link: https://lore.kernel.org/20260719161136.90191-1-sj@kernel.org
Fixes: 42f994b714 ("mm/damon/core: implement scheme-specific apply interval")
Signed-off-by: SJ Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> # 6.7.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
SJ Park 2026-07-19 09:11:33 -07:00 committed by Andrew Morton
parent 308ab73e97
commit 6c25083f7a
1 changed files with 3 additions and 2 deletions
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5
mm/damon/ops-common.c
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@ -111,8 +111,9 @@ int damon_hot_score(struct damon_ctx *c, struct damon_region *r,
unsigned int age_weight = s->quota.weight_age;
int hotness;
freq_subscore = r->nr_accesses * DAMON_MAX_SUBSCORE /
damon_nr_samples_per_aggr(&c->attrs);
freq_subscore = mult_frac(damon_nr_accesses_mvsum(r, c),
DAMON_MAX_SUBSCORE,
damon_nr_samples_per_aggr(&c->attrs));
age_in_sec = (unsigned long)r->age * c->attrs.aggr_interval / 1000000;
if (age_in_sec)