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 X-Spam-Level: X-Spam-Status: No, score=-5.5 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BE3FEC43381 for ; Wed, 13 Mar 2019 19:48:52 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 7ED9A2146E for ; Wed, 13 Mar 2019 19:48:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=cmpxchg-org.20150623.gappssmtp.com header.i=@cmpxchg-org.20150623.gappssmtp.com header.b="OnWbLuxJ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7ED9A2146E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=cmpxchg.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 0E2B88E001D; Wed, 13 Mar 2019 15:48:52 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 093088E0001; Wed, 13 Mar 2019 15:48:52 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E9BBB8E001D; Wed, 13 Mar 2019 15:48:51 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from mail-yw1-f72.google.com (mail-yw1-f72.google.com [209.85.161.72]) by kanga.kvack.org (Postfix) with ESMTP id BD10E8E0001 for ; Wed, 13 Mar 2019 15:48:51 -0400 (EDT) Received: by mail-yw1-f72.google.com with SMTP id h3so3221080ywe.21 for ; Wed, 13 Mar 2019 12:48:51 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:dkim-signature:date:from:to:cc:subject :message-id:references:mime-version:content-disposition:in-reply-to :user-agent; bh=ctaB5au7utl3Gx2JywUyoePNtfp/SVRLeNPeDseyDJs=; b=CXxdcO1Aj2qgMQ6HoEsCAMe5pEuUYnalH6Tn10f2HUFFFYYT+xXRVmWn10J7uDh4dT KJ3Hv57JUTOYsU7oxOTM5crkhw2Ery59NsEAC3Zb/mVgnLtU/phuSJTx8PvZ+QLLKXyW F5qSW9r1hZUfFszSbYqTeAjh5SBB9K8V7Isix2p4KWJOxhlbfCSomdICIvztYnCYxwBn nEcAapJpRy3IDW/PPWjoNUh8cb3NCUXY5CaCojMbvVp00d2iDt+eTkBgZcftIlVx/fDQ c19iuJ2ryn7XUnG/cqRSgUgTF5sA/U2YshY3fXdS711G5i2/HdxEAC3S/9CWu1/Zt+SV 3R6g== X-Gm-Message-State: APjAAAV8rTQWL+s6lCJnYY4OOjYb+8VWF7bOCCo2ph5TWRDGxS2Ifrfo GJe/TnN9wssZ9puj65H/TT23sLhFuYxgxzutQK4MTG+WSzocyqP4zUhifBzAfBTKWB+ThzarUN7 tegChDFLl+5dJYeX6R9lk0wIyIYaM9GGDzGJd1vUEzbMPsL6jkzUuG/zGnwbslUw6h1hE/5YFu8 LcnELDgsH8iEdmlt6jmbwwQL8RxvP6g37rneECRtN8PEKweHfEWlj08q4XUc1qXFHM5UaSIfwxn +h3q1Yl2PBlvGMSjo6WVYvxjmMLE/NlR6m+j2iLsMRMMsSqaWwB89Li+rI4rko49cUlCGbfzm2p PvUClnIoJdwbh8cUDl5FCTv6sLh3NuIkhZvqr483BD7nzrxhw0GqJ1PcITzaYSzEUE0te/kfhUt J X-Received: by 2002:a81:142:: with SMTP id 63mr36676145ywb.119.1552506531392; Wed, 13 Mar 2019 12:48:51 -0700 (PDT) X-Received: by 2002:a81:142:: with SMTP id 63mr36676111ywb.119.1552506530591; Wed, 13 Mar 2019 12:48:50 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1552506530; cv=none; d=google.com; s=arc-20160816; b=wHDgGqr1FeYUsr7bAEBhIdTOR70xUAwPGUXqn72xsk2KlcQ4g+tQeFv91AJW4nVGXf uHEwuslIwg+hvj3hdyaiS8YLCldKIYtebTwVYowi3mSbfMH/P4TSPog8xINB3BI5JydG zmMHUZBpHrqvYt49FsUEQX40VM+CbPhzCJL4rNwvWJ5wfhgsbm1LO8VkTvy2lKsJb2pp 01BQCtgpBfA2TSoPljUlcj+MRvj9UcUSsI4ul2l2wLdjuJ84xe+DyE/vfnBtjGgYR8dP 7ee3B+yYtcT7rlicL0whb7WE5eZTXn6zkqbPTBquRcRWZTiWtmEgvduvKmF7Bo2OEFsd Jttw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=user-agent:in-reply-to:content-disposition:mime-version:references :message-id:subject:cc:to:from:date:dkim-signature; bh=ctaB5au7utl3Gx2JywUyoePNtfp/SVRLeNPeDseyDJs=; b=iV5Vk7ThrALrj5kpRWwDqPrbtI3vzpFmRwpqnUnKfVVKCdc6yLaWHxXSn0yQAvWpb6 xc0pggP4kUPR0Q010TBXsP7ZyRFfBRREg5J7htlyS3nx2aUmWQmLOiFAS2tLthosLML3 7I+x6JTwH0GxNNQ0tG5aps0JYvTahc9nxX7Tqv+5i863UexRPURWSq2789vafFaluahN sIyph8BhR9uTBKVj1Ely22wrMuGxLu4GqMHB+S9fFG/4ZWF1ug4wcxA5+SRf6oXywz1w MigR0xouM6XaNUjTW25IUbHf9aHKNw3W2A0JeLeaQ0bEYpPmBP1KhQqL/FqaXAxjxl1i QxeQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@cmpxchg-org.20150623.gappssmtp.com header.s=20150623 header.b=OnWbLuxJ; spf=pass (google.com: domain of hannes@cmpxchg.org designates 209.85.220.65 as permitted sender) smtp.mailfrom=hannes@cmpxchg.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=cmpxchg.org Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id b190sor1593976ywe.142.2019.03.13.12.48.47 for (Google Transport Security); Wed, 13 Mar 2019 12:48:48 -0700 (PDT) Received-SPF: pass (google.com: domain of hannes@cmpxchg.org designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@cmpxchg-org.20150623.gappssmtp.com header.s=20150623 header.b=OnWbLuxJ; spf=pass (google.com: domain of hannes@cmpxchg.org designates 209.85.220.65 as permitted sender) smtp.mailfrom=hannes@cmpxchg.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=cmpxchg.org DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cmpxchg-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=ctaB5au7utl3Gx2JywUyoePNtfp/SVRLeNPeDseyDJs=; b=OnWbLuxJUnJM/J0oMb5kwfpcPSBBvgndkRUIdj1Of5FyPfO08VbDXbFmlNVzmRVL4p mQUwSvPlqYMcNLAJ8YCO7rRrcAV1iQfb8V4MXysCtaiVX9tmNvRZyAhzulMzdmbBNBPe MUO0U1YNBaS7QOW7PfCODPfZx/VPVPHBWGL7tP6MRvtki+Lt3mB6HiAy+qhMUcq6qaE9 1mJmoPPW8nM2UUjSlsB8ZZLSjXXvTKmQKacK0PgYLsvmmpBn6wVl3F3yTeaffyzrXKDg F904F9pO0vhglCrjhO8Rw0eeAEUHQDraSLAuvtSFLxPt9PbJ5TlwYTocy0p0jtiSADoj 1xfw== X-Google-Smtp-Source: APXvYqyAlTREA7MYT/TBB0yTNoQ3Snqb0+I/lcx9HWdX+jEh4Hya3vdEqloX9ZGZMvipUA07u+QWRQ== X-Received: by 2002:a81:c546:: with SMTP id o6mr4753314ywj.508.1552506527798; Wed, 13 Mar 2019 12:48:47 -0700 (PDT) Received: from localhost ([2620:10d:c091:200::468c]) by smtp.gmail.com with ESMTPSA id h5sm5599866ywh.3.2019.03.13.12.48.46 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 13 Mar 2019 12:48:47 -0700 (PDT) Date: Wed, 13 Mar 2019 15:48:46 -0400 From: Johannes Weiner To: Roman Gushchin Cc: linux-mm@kvack.org, kernel-team@fb.com, linux-kernel@vger.kernel.org, Tejun Heo , Rik van Riel , Michal Hocko , Roman Gushchin Subject: Re: [PATCH v3 6/6] mm: refactor memcg_hotplug_cpu_dead() to use memcg_flush_offline_percpu() Message-ID: <20190313194846.GA6683@cmpxchg.org> References: <20190313183953.17854-1-guro@fb.com> <20190313183953.17854-7-guro@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190313183953.17854-7-guro@fb.com> User-Agent: Mutt/1.11.3 (2019-02-01) 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: On Wed, Mar 13, 2019 at 11:39:53AM -0700, Roman Gushchin wrote: > It's possible to remove a big chunk of the redundant code by making > memcg_flush_offline_percpu() to take cpumask as an argument and flush > percpu data on all cpus belonging to the mask instead of all possible cpus. > > Then memcg_hotplug_cpu_dead() can call it with a single CPU bit set. > > This approach allows to remove all duplicated code, but safe the > performance optimization made in memcg_flush_offline_percpu(): > only one atomic operation per data entry. > > for_each_data_entry() > for_each_cpu(cpu. cpumask) > sum_events() > flush() > > Otherwise it would be one atomic operation per data entry per cpu: > for_each_cpu(cpu) > for_each_data_entry() > flush() > > Signed-off-by: Roman Gushchin Acked-by: Johannes Weiner