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[209.85.220.65]) by mx.google.com with SMTPS id d191sor520717ywa.55.2019.03.13.09.00.19 for (Google Transport Security); Wed, 13 Mar 2019 09:00:19 -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=dGdqiWPo; 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=Kfs3heF+8ue5fPhJOE/1L32aZGxH5YHBEa9Vc48MxT0=; b=dGdqiWPo1BOx1Hrm9Yb+fmpMIctPhEyDjRuPEMfrsn/Kt3uPznTjItkUMy2bpQMkQq XOYyDXCPqUUbQyfrVo9hxOy8cYORZfSPejYoVDe4rwugqGjQrmP7bE6g+d4055mdv94g f8F56Qk5Irl6ERWKfsSoNNUIZ90EecAB46rjEJFZ6Zs/jfURwKv0AmY+pVvS8fwmIcRK I5RYS3nVJO4MTfBMA2OoQpzpmlWz3gRLoT0hp6pdkH6T0vjyZJRkCaaq+o5Kk3mLCC+X jHtDw6/k3XpwqdP0ueQ4wM2KfvFTVxbuxDX4IWvI6ywSfu9pTCyuImllQMhznFZh41Jj iecQ== X-Google-Smtp-Source: APXvYqxxouOQGLIOlx87tzAbVKhhhLdCSYZWRYS4+anzMp8teZfEjVRDQ/PJhjsFB5CB1/xBLaz/JQ== X-Received: by 2002:a81:9ad1:: with SMTP id r200mr12040290ywg.287.1552492819181; Wed, 13 Mar 2019 09:00:19 -0700 (PDT) Received: from localhost ([2620:10d:c091:200::2:9a85]) by smtp.gmail.com with ESMTPSA id q1sm5606033ywe.14.2019.03.13.09.00.18 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 13 Mar 2019 09:00:18 -0700 (PDT) Date: Wed, 13 Mar 2019 12:00:17 -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 v2 5/6] mm: flush memcg percpu stats and events before releasing Message-ID: <20190313160017.GA31891@cmpxchg.org> References: <20190312223404.28665-1-guro@fb.com> <20190312223404.28665-6-guro@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190312223404.28665-6-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 Tue, Mar 12, 2019 at 03:34:02PM -0700, Roman Gushchin wrote: > Flush percpu stats and events data to corresponding before releasing > percpu memory. > > Although per-cpu stats are never exactly precise, dropping them on > floor regularly may lead to an accumulation of an error. So, it's > safer to flush them before releasing. > > To minimize the number of atomic updates, let's sum all stats/events > on all cpus locally, and then make a single update per entry. > > Signed-off-by: Roman Gushchin Acked-by: Johannes Weiner Do you mind merging 6/6 into this one? That would make it easier to verify that the code added in this patch and the code removed in 6/6 are indeed functionally equivalent.