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Sat, 12 Sep 2026 05:44:03 -0700 (PDT) Received: from celestia ([2402:1980:8858:8cc0:7bda:d54a:257:22ec]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-39d95713602sm10294840a91.11.2026.09.12.05.44.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 12 Sep 2026 05:44:03 -0700 (PDT) From: Liew Rui Yan To: Cc: Liew Rui Yan , SJ Park , Andrew Morton , damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [RFC PATCH] mm/damon/core: add short circuit for temporal-goal schemes in damos_adjust_quota() Date: Sat, 12 Sep 2026 20:43:12 +0800 Message-ID: <20260912124406.96535-1-aethernet65535@gmail.com> X-Mailer: git-send-email 2.55.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit When using the temporal auto-tuning algorithm, the effective size quota becomes zero once the goal is [over-]achieved. In this situation, damos_adjust_quota() still calculates quota->min_score for it. However, this min_score will not be used in this window, because in damon_do_apply_schemes(), damos_quota_is_full() will always returns true, preventing the scheme from being applied to any region. Therefore, add a short circuit for temporal-goal algorithm schemes to early return from damos_adjust_quota() before calculating min_score. Signed-off-by: Liew Rui Yan --- I tested with virtme-ng + perf on a Proactive Memory Reclaim workload; within measurement noise (~3%), no measurable difference was observed. The purpose of this patch is to reduce unnecessary operations (calculating min_score). But, I'd like to know if this patch needs to demonstrate that it provides better performance before it's merged. --- mm/damon/core.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/mm/damon/core.c b/mm/damon/core.c index ce8c6f99106e..fdcea989f0e0 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -3320,6 +3320,8 @@ static void damos_adjust_quota(struct damon_ctx *c, struct damos *s) if (!c->ops.get_scheme_score) return; + if (quota->esz == 0) + return; /* Fill up the score histogram */ memset(c->regions_score_histogram, 0, -- 2.55.0