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 DBD5B37647E; Wed, 20 May 2026 06:29:10 +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=1779258552; cv=none; b=Ww7JzuaD2AaBMro/KZ9DUlbELn/MCJ1e8Qz99AdfPzG6PGpClAtDY4txpYRUqwEVpAxZGMLw3lzkcNkXLt/vneZCRwkUFVDbkDV5zQ6/9veM1gZEAUXFg83w93rZJmdivYKCrlzonPiiYqFrzYjn4Uj0wy6DDbQpH7f34t/TKK8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779258552; c=relaxed/simple; bh=lpSts6uYgJTwQnR0tqrpn9gyftbdM1/PtbAdTF8k4SA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=I36pBK4kRRPFgq9ikEcKwWcHYabQ12FPm72SbZ3hm1RNr0XPVzY4JwLVgsBzDc3aLaIIWZWkE/jNbkJJZ+lcGZdNb5Q1xWJtBMfXzqG8iJLaq8t9VyNa1NMPR17xn64ESWLLBgSE+P61pSxu2Rc3OA+n+/kuChD+dmZTvsoZY6I= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=PuffpziA; 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="PuffpziA" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 979101F00894; Wed, 20 May 2026 06:29:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779258550; bh=i4QYAEHbDCvNou4iBTdigpX/qcP0blVfRQa9MnkoH2M=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=PuffpziAWFwnPx+GwTm5I81IktL90Ytz6cqBL47N2tAApCaD1794IXBGY0MSedK1C rw9QV5bzVvjay2UlCCZh7TRIgnnQK2fbmRifTouq2ueSu7LbHv9LpVsigyUKmgTC3F 0qGGzoyErrEbYAcD9JwZvu8YzEgjED1gTzEwTy6Z6ir7jFizIMgUpQGricmQ7asNhx R1OdbxXr1HAzcDYFQi6MxHFUFU9NOfNhWKFX9qS153UpEoNweD36vEjhxg47gsv2Q8 qLDyDmf471SMXGT3UL9iSD7QkAUxAxP+hZrJyjlxHi9K4QDMODlGE91820cxFthxKP Z3YKcpdKviQJA== From: SeongJae Park To: Cc: SeongJae Park , Andrew Morton , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [RFC PATCH 09/14] mm/damon/core: remove damon_verify_nr_regions() Date: Tue, 19 May 2026 23:28:41 -0700 Message-ID: <20260520062858.167011-10-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260520062858.167011-1-sj@kernel.org> References: <20260520062858.167011-1-sj@kernel.org> 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 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 22327a23c7e57..b2d268c4102db 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