linux-kernel - [PATCH 7/8] mm/damon/core: skip updating nr_accesses

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Date:   Fri, 15 Sep 2023 02:52:50 +0000
From:   SeongJae Park <sj@...nel.org>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     SeongJae Park <sj@...nel.org>, damon@...ts.linux.dev,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: [PATCH 7/8] mm/damon/core: skip updating nr_accesses_bp for each aggregation interval

damon_merge_regions_of(), which is called for each aggregation interval,
updates nr_accesses_bp to nr_accesses * 10000.  However, nr_accesses_bp
is updated for each sampling interval via damon_moving_sum() using the
aggregation interval as the moving time window.  And by the definition
of the algorithm, the value becomes same to discrete-window based sum
for each time window-aligned time.  Hence, nr_accesses_bp will be same
to nr_accesses * 10000 for each aggregation interval without explicit
update.  Remove the unnecessary update of nr_accesses_bp in
damon_merge_regions_of().

Signed-off-by: SeongJae Park <sj@...nel.org>
---
 mm/damon/core.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/mm/damon/core.c b/mm/damon/core.c
index 29ee1fc18393..45cc108c0fe1 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -1141,8 +1141,6 @@ static void damon_merge_regions_of(struct damon_target *t, unsigned int thres,
 		else
 			r->age++;

-		r->nr_accesses_bp = r->nr_accesses * 10000;
-
 		if (prev && prev->ar.end == r->ar.start &&
 		    abs(prev->nr_accesses - r->nr_accesses) <= thres &&
 		    damon_sz_region(prev) + damon_sz_region(r) <= sz_limit)
-- 
2.25.1