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 B07E2408015; Thu, 21 May 2026 14:34:40 +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=1779374082; cv=none; b=f2h8Jgfz2F3OlyxO8b8Y8T1Zlz1lJW4hlwu/ZarxM2uNodQKVll2+t5N3ameLer+VXwsIfTJ3onv+LUrRp98r0KD7iJTdwLOXuy08eoXIC1eWNUb1j8DzdxYJ5BH4uCjrJh78GRwvlXedONy4pRipYPuqfPsp1/2MdNgz1c7bsg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779374082; c=relaxed/simple; bh=60hNbVqTSP21yPGuac3bHL+OYhfMoIX08QASyu0GIRA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=nPPnAqwdriGDWnxjBe1DrHr5qT+zugSjpKt7H2tbLG4a2KaU0JZs9elxbDegljOBCGtzynhXq+vGT6uMgWTjQBchm87wfZZMV4QtlRjgi0Q9QgcD0E7frvfgTQQL394ewWNQDw15g4KvEooDkfEAHo/qdZuQ6zgtoIMlScdnTME= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=JtY5kwgF; 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="JtY5kwgF" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5EF3F1F00A3E; Thu, 21 May 2026 14:34:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779374080; bh=rlDrTS/qDNMBtSrkkbpm6odK2sEC/p6nHvamOoXHSXU=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=JtY5kwgF4NwiR351gN+IX2c7r/wJR+0aeF7H+sK8LicM/7/DxyiXigb0TCZ1ozEla 0RsIyyO4Lbz+bYSE71gTiHiEncqPdNwEjAwFHjE9PFGwQXfptpQx8MVzKARWNuF4j5 bUXioO3JgTlq0Qggl4aqdkeJUsipCmLdCYQHj4ztcuCwMGAMYvGS+k9HedAVX2vIkx qOG7euYJG+CuXuKHcsz+GPig1oDr2n1hMWQtC59Y1CNr0J8yBnRu1umoNlKsHJFzM/ SbfuvdcQFxDNkXl7ogp47u87t/ROI5Loqe5V7v/dmaWoOgz8drDrXyVXyc35TDD/p0 JUEYKQKQluElw== 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 v1.2 09/14] mm/damon/core: remove damon_verify_nr_regions() Date: Thu, 21 May 2026 07:34:19 -0700 Message-ID: <20260521143428.83157-10-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260521143428.83157-1-sj@kernel.org> References: <20260521143428.83157-1-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 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