From: SJ Park <sj@kernel.org>
Cc: SJ Park <sj@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
damon@lists.linux.dev, linux-kernel@vger.kernel.org,
linux-mm@kvack.org
Subject: [RFC PATCH v2 03/10] mm/damon/core: use mult_frac() in damon_feed_loop_next_input()
Date: Wed, 16 Sep 2026 21:05:29 -0700 [thread overview]
Message-ID: <20260917040537.107341-4-sj@kernel.org> (raw)
In-Reply-To: <20260917040537.107341-1-sj@kernel.org>
damon_feed_loop_next_input() does its best effort overflow protection.
score_goal_diff is always smaller than goal (10,000). Hence the
calculation can be replaced to use mult_frac() without concerning the
overflow. Use mult_frac().
Signed-off-by: SJ Park <sj@kernel.org>
---
mm/damon/core.c | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)
diff --git a/mm/damon/core.c b/mm/damon/core.c
index 0299729e79ed9..7bbbd44379301 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -2928,11 +2928,7 @@ static unsigned long damon_feed_loop_next_input(unsigned long last_input,
return min_input;
score_goal_diff = abs_diff(score, goal);
-
- if (last_input < ULONG_MAX / score_goal_diff)
- compensation = last_input * score_goal_diff / goal;
- else
- compensation = last_input / goal * score_goal_diff;
+ compensation = mult_frac(last_input, score_goal_diff, goal);
if (over_achieving)
return max(last_input - compensation, min_input);
--
2.47.3
next prev parent reply other threads:[~2026-09-17 4:05 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-17 4:05 [RFC PATCH v2 00/10] mm/damon: improve readability, clarity and test coverage SJ Park
2026-09-17 4:05 ` [RFC PATCH v2 01/10] mm/damon/api: remove NR_DAMOS_FILTER_TYPES SJ Park
2026-09-17 4:05 ` [RFC PATCH v2 02/10] mm/damon/core: use abs_diff() in damon_feed_loop_next_input() SJ Park
2026-09-17 4:05 ` SJ Park [this message]
2026-09-17 4:05 ` [RFC PATCH v2 04/10] mm/damon/core: set damon_ctx->walk_control_obsolete in damon_new_ctx() SJ Park
2026-09-17 4:05 ` [RFC PATCH v2 05/10] mm/damon/core: document damon_call()/damon_start() race hang issue SJ Park
2026-09-17 4:05 ` [RFC PATCH v2 06/10] mm/damon/paddr: remove pa parameter from damon_pa_filter_pass() SJ Park
2026-09-17 4:05 ` [RFC PATCH v2 07/10] mm/damon/tests/core-kunit: test eligible_mem_bp commitment SJ Park
2026-09-17 4:05 ` [RFC PATCH v2 08/10] mm/damon/tests/core-kunit: add probe_hits_wsum damos filter commit test SJ Park
2026-09-17 4:05 ` [RFC PATCH v2 09/10] selftests/damon/sysfs_memcg_path_leak: fail only for real DAMON leak SJ Park
2026-09-17 4:05 ` [RFC PATCH v2 10/10] Docs/mm/damon/design: clarify bp is basis point SJ Park
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