From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 91C2FC3601E for ; Fri, 11 Apr 2025 00:03:25 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 50CBB280147; Thu, 10 Apr 2025 20:03:24 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 4BA6F280138; Thu, 10 Apr 2025 20:03:24 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3A883280147; Thu, 10 Apr 2025 20:03:24 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 1BFDA280138 for ; Thu, 10 Apr 2025 20:03:24 -0400 (EDT) Received: from smtpin15.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 2A192AFA34 for ; Fri, 11 Apr 2025 00:03:24 +0000 (UTC) X-FDA: 83319813528.15.85745B4 Received: from out-179.mta1.migadu.com (out-179.mta1.migadu.com [95.215.58.179]) by imf10.hostedemail.com (Postfix) with ESMTP id 619B5C0007 for ; Fri, 11 Apr 2025 00:03:22 +0000 (UTC) Authentication-Results: imf10.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=HC1zfhPJ; spf=pass (imf10.hostedemail.com: domain of roman.gushchin@linux.dev designates 95.215.58.179 as permitted sender) smtp.mailfrom=roman.gushchin@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1744329802; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=+lIX9/v11+BoYiEBQHEK4lg4jIirIDoOfwf7R8IM3SU=; b=GfmYXbvBV67Nm9k26WEjVgq0d+CEF/taiELYs05RsWgs0nQqTRIQOoddBRFfGXTFFft9X5 OTG+LhA4g7AsHHTHl2pFONuIecJpjW1OKShIl3apISJiYIUGrsQewGA3L9BCX2codenTzs 7F4UpB2KTJlliuCIGKbQMcgrG9UJPIw= ARC-Authentication-Results: i=1; imf10.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=HC1zfhPJ; spf=pass (imf10.hostedemail.com: domain of roman.gushchin@linux.dev designates 95.215.58.179 as permitted sender) smtp.mailfrom=roman.gushchin@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1744329802; a=rsa-sha256; cv=none; b=UsoDkjEzAF9JKUWeMEDpX/+QXHfRNzdskBLvSyrCdDM/1aFFPHQODGu0o4/Nm6Yx8tfMbg 57W/EKkeg2ccsBj00AxnDrwv/81oypuyYRLSoWoa7Vu9RMMwOEC34ux/qbqXhCN7AZvQQR 99xu7wWh7eFfNo3yanLNvA1U1A/nZtU= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1744329800; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=+lIX9/v11+BoYiEBQHEK4lg4jIirIDoOfwf7R8IM3SU=; b=HC1zfhPJZ/60exfVRt4XF6oPqJKIMImvaMvaCfL/G24AYsjDxLyxM9Rq3G9ERmU9rvDaE6 8wxjT+1vp/Pxqt5PX6jG3BLY5s0yvpZ05cWa8bdCCrxlhu5kR3t9wjjLZPQxS7UoEKk2eE B5GRUu7+54OJO+Y9/2aKgXqzufiWv2o= From: Roman Gushchin To: Shakeel Butt Cc: Andrew Morton , Johannes Weiner , Michal Hocko , Muchun Song , Yosry Ahmed , Waiman Long , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Meta kernel team Subject: Re: [PATCH v2] memcg: optimize memcg_rstat_updated In-Reply-To: <20250410025752.92159-1-shakeel.butt@linux.dev> (Shakeel Butt's message of "Wed, 9 Apr 2025 19:57:52 -0700") References: <20250410025752.92159-1-shakeel.butt@linux.dev> Date: Fri, 11 Apr 2025 00:03:14 +0000 Message-ID: <7ia4semfzhrx.fsf@castle.c.googlers.com> MIME-Version: 1.0 Content-Type: text/plain X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: 619B5C0007 X-Rspamd-Server: rspam05 X-Rspam-User: X-Stat-Signature: ih47wu117gfoz7qyh3d75d7hf9cz1f1k X-HE-Tag: 1744329802-91201 X-HE-Meta: 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 sUzapRkC VvKR9EawhGVmnTM7vLSNJKg2orLH9lXgV+BHt7k8pAvIJqPDkcdUXZteXtk11OdxgHKAPNRepeJ1afzaGn1PQIbdXsHIhf3fsoevJMcR0nrZygEK5EPc3TFPm6j5cxmfDEUJtTsYEq/RbndE= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Shakeel Butt writes: > Currently the kernel maintains the stats updates per-memcg which is > needed to implement stats flushing threshold. On the update side, the > update is added to the per-cpu per-memcg update of the given memcg and > all of its ancestors. However when the given memcg has passed the > flushing threshold, all of its ancestors should have passed the > threshold as well. There is no need to traverse up the memcg tree to > maintain the stats updates. > > Perf profile collected from our fleet shows that memcg_rstat_updated is > one of the most expensive memcg function i.e. a lot of cumulative CPU > is being spent on it. So, even small micro optimizations matter a lot. > This patch is microbenchmarked with multiple instances of netperf on a > single machine with locally running netserver and we see couple of > percentage of improvement. > > Signed-off-by: Shakeel Butt Acked-by: Roman Gushchin Thanks!