From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D464F48095F; Fri, 22 May 2026 15:40:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779464439; cv=none; b=sZY6D9KB7D/clQ8ZBK5qTzZ2K+yI9aOOnitp/rXX3dT/YJZPgLyZ8oJqgQJ/+gNJwMU9WvMAyEbxaS4a//B1q6K9S+q6zyJTEiihTYTeV/+kSXIBn7azWPI8p5D9SrAUQa7wMUMsDAXboVUbxyACLywNzboYytxNHf4N7cnW0I4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779464439; c=relaxed/simple; bh=60hNbVqTSP21yPGuac3bHL+OYhfMoIX08QASyu0GIRA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=H7DNMCFPGjY7FmLYJZc53MgAqNpIp6SQ2iMPScGrnsc8cU4jcA66tjsAG9uWG2UjCuy+vlUv/yuxNe912j6P3yk8ut9B5ffidFBMUpk3Q8NPO+m69RdfpxzjYTVIf2B/KfV2nuel3Xji2eFt22SCy+NwH2+rxEtFUOvFoab7GbM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=PRCm+J+m; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="PRCm+J+m" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8A5FA1F00A3D; Fri, 22 May 2026 15:40:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779464437; bh=rlDrTS/qDNMBtSrkkbpm6odK2sEC/p6nHvamOoXHSXU=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=PRCm+J+mZl77Sc1wSkhjFvMo6gfXN2YkuIeCJ2pHOE8X0WlwQ5pbBuOyF3jt4nZRH ben/v8RpD9Pd9a0vOPWvv/7KDogs4XMbaVgxOaUBnBEBsAYLYfxu2ZzvDwzz7gPfgB Wbemfq7GP0Zvv9mudLM58kVzCVUJrZfRXcwA+KgZCQ8VNMS6PcrhiKXoF7eEDdnZh3 KeDyvyuO1x6tv8oXAa9KaW+Ju/0vxydczqLPpjzU9kn60SWU1dqC2p1uaRNfbQG9EU Hgo8plxdJhtTC3ANO7HrR39qRyGH9uagAnkV304IxGfM7N2D6x1iSepAYmeWRyflMy p0Of15I8kFNig== From: SeongJae Park To: Andrew Morton Cc: SeongJae Park , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH 09/14] mm/damon/core: remove damon_verify_nr_regions() Date: Fri, 22 May 2026 08:40:20 -0700 Message-ID: <20260522154026.80546-10-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260522154026.80546-1-sj@kernel.org> References: <20260522154026.80546-1-sj@kernel.org> Precedence: bulk X-Mailing-List: damon@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit When CONFIG_DAMON_DEBUG_SANITY is enabled, damon_verify_nr_regions() is called for each damon_nr_regions() invocation. damon_veify_nr_regions() iterates all regions. damon_nr_regions() is called for each region in kdamond_reset_aggregated() and damos_apply_scheme(). Hence it imposes O(n**2) overhead where n is the number of regions. Though the verification is enabled only under DAMON_DEBUG_SANITY, which is not for production use cases, it could be too high overhead. Meanwhile, damon_verify_ctx() is doing the damon_nr_regions() test. Because damon_verify_ctx() is called for each kdamond_call(), the test coverage from damon_verify_ctx() could be sufficient. Remove damon_nr_regions() verification. Signed-off-by: SeongJae Park --- mm/damon/core.c | 19 ------------------- 1 file changed, 19 deletions(-) diff --git a/mm/damon/core.c b/mm/damon/core.c index 9cde5b47b9585..265d51ade25bf 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -686,27 +686,8 @@ void damon_destroy_target(struct damon_target *t, struct damon_ctx *ctx) damon_free_target(t); } -#ifdef CONFIG_DAMON_DEBUG_SANITY -static void damon_verify_nr_regions(struct damon_target *t) -{ - struct damon_region *r; - unsigned int count = 0; - - damon_for_each_region(r, t) - count++; - WARN_ONCE(count != t->nr_regions, "t->nr_regions (%u) != count (%u)\n", - t->nr_regions, count); -} -#else -static void damon_verify_nr_regions(struct damon_target *t) -{ -} -#endif - unsigned int damon_nr_regions(struct damon_target *t) { - damon_verify_nr_regions(t); - return t->nr_regions; } -- 2.47.3