From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 4BC7E2C11CD; Mon, 2 Feb 2026 04:49:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770007747; cv=none; b=OXNaThxk1WpFfO07KYBwAQLLr3yAmjtkjG8UDG3L13ludjFqsJ/BgFweCaKZ2d1Ml1Kqrx65o6CTH4FejcLXKfVNjjdT+aFLTvF5zGGUFstqqCmOMzGOLj7x3pEt2sgzsVZBnVkEsGIxvPl9t93/z6paFtQmaCd1DazGRu/i8Hg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770007747; c=relaxed/simple; bh=SMTLwTiGXiPrzkV2SsL2OnW5kJvjDOPABC51IhmEd1g=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=P31t6ZST8Fwk0ApkcnW31hwkdQApVv3H1Gly6qtl2z0aeRbV9mG8DJ3U2oH6mkenUD6tCZ+fSHEcJb2soHV4VcNHQfYOohv/1eL3/XYBYQ2aRvqMvu9KoHKdtG2bzL/amsW/HFQ2KF66hVp7BlbJ/orXupfcz9Kvgjg6aBvQsOk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id E0533339; Sun, 1 Feb 2026 20:48:58 -0800 (PST) Received: from [10.164.136.51] (unknown [10.164.136.51]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 764743F740; Sun, 1 Feb 2026 20:49:01 -0800 (PST) Message-ID: <2638bd96-d8cc-4733-a4ce-efdf8f223183@arm.com> Date: Mon, 2 Feb 2026 10:18:52 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/4] memcg: use mod_node_page_state to update stats To: Shakeel Butt Cc: Andrew Morton , Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , Harry Yoo , Qi Zheng , Vlastimil Babka , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Meta kernel team References: <20251110232008.1352063-1-shakeel.butt@linux.dev> <20251110232008.1352063-2-shakeel.butt@linux.dev> <1052a452-9ba3-4da7-be47-7d27d27b3d1d@arm.com> Content-Language: en-US From: Dev Jain In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 02/02/26 9:56 am, Shakeel Butt wrote: > On Thu, Jan 29, 2026 at 06:35:21PM +0530, Dev Jain wrote: >> On 11/11/25 4:50 am, Shakeel Butt wrote: >>> The memcg stats are safe against irq (and nmi) context and thus does not >>> require disabling irqs. However some code paths for memcg stats also >>> update the node level stats and use irq unsafe interface and thus >>> require the users to disable irqs. However node level stats, on >>> architectures with HAVE_CMPXCHG_LOCAL (all major ones), has interface >>> which does not require irq disabling. Let's move memcg stats code to >>> start using that interface for node level stats. >>> >>> Signed-off-by: Shakeel Butt >>> --- >> Hello Shakeel, >> >> We are seeing a regression in micromm/munmap benchmark with this patch, on arm64 - >> the benchmark mmmaps a lot of memory, memsets it, and measures the time taken >> to munmap. Please see below if my understanding of this patch is correct. > Thanks for the report. Are you seeing regression in just the benchmark > or some real workload as well? Also how much regression are you seeing? > I have a kernel rebot regression report [1] for this patch as well which > says 2.6% regression and thus it was on the back-burner for now. I will > take look at this again soon. The munmap regression is ~24%. Haven't observed a regression in any other benchmark yet. > > [1] https://lore.kernel.org/all/202512101408.af3876df-lkp@intel.com/ >