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[209.85.220.65]) by mx.google.com with SMTPS id t79sor13366197itb.25.2019.04.12.02.48.43 for (Google Transport Security); Fri, 12 Apr 2019 02:48:43 -0700 (PDT) Received-SPF: pass (google.com: domain of laoar.shao@gmail.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=jyT0I88f; spf=pass (google.com: domain of laoar.shao@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=laoar.shao@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=idRrgLQbh43uv5SWzcGBZ8Bw6NnS0EFw56f1NhH2bmU=; b=jyT0I88fbQsWDDkcpAHsTB4dPiS8GXwBOaA7w1gX7CjhR5ckSeSU3vVufWyzwg+S1N UN2mADQzD8sYoaoJ9PMXtIZvU9Pq2QtBBnB0TjjHxTRBT00PI/PoAMEGY4qfBOZCpVey rLyvgs2FNrUjDQLKpuUJpv20nwwQj6pptaATym9VKQXuRRcTXltdZLhyvxT48v9rGNzq DEWcgU1eskhuQUdnKN/S+IC6lyTtrL4mwnD92XJFh4F2kMZ+E3dFBS8xyKggTLVezoye tOPShNTuGAvY1GLsvlrCmhKwxxrzan7jyRZndfVAt7BdldLN3kkCRji2xVSctdnLvzvq i0EQ== X-Google-Smtp-Source: APXvYqxjGJJ/A6mt8SH18qyn0SuldDTOBgOjI9JM7PPodXcwvazbhCWq4k7iNxWIIZuEny97Xt+vxPg9cRU74KaHymM= X-Received: by 2002:a24:5751:: with SMTP id u78mr12491332ita.135.1555062523330; Fri, 12 Apr 2019 02:48:43 -0700 (PDT) MIME-Version: 1.0 References: <20190411122659.GW10383@dhcp22.suse.cz> <20190411133300.GX10383@dhcp22.suse.cz> <20190411151039.GY10383@dhcp22.suse.cz> <20190412063417.GA13373@dhcp22.suse.cz> <20190412090929.GE13373@dhcp22.suse.cz> <20190412093641.GG13373@dhcp22.suse.cz> In-Reply-To: <20190412093641.GG13373@dhcp22.suse.cz> From: Yafang Shao Date: Fri, 12 Apr 2019 17:48:07 +0800 Message-ID: Subject: Re: [PATCH] mm/memcg: add allocstall to memory.stat To: Michal Hocko Cc: Johannes Weiner , Chris Down , Andrew Morton , Cgroups , Linux MM , shaoyafang@didiglobal.com Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000033, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Apr 12, 2019 at 5:36 PM Michal Hocko wrote: > > On Fri 12-04-19 17:29:04, Yafang Shao wrote: > > On Fri, Apr 12, 2019 at 5:09 PM Michal Hocko wrote: > [...] > > > > Then we can do some trace for this memcg, i.e. to trace how long the > > > > applicatons may stall via tracepoint. > > > > (but current tracepoints can't trace a specified cgroup only, that's > > > > another point to be improved.) > > > > > > It is a task that is stalled, not a cgroup. > > > > But these tracepoints can't filter a speficied task neither. > > each trace line output should cotain a pid, no? But that's not enough. Some drawbacks, - the PID is variable, and it is not so conveninet to get the tasks from this PID. i.e. when you use pidof to get the tasks, it may already exit and you get nothing. - the traceline don't always contain the task names. - if we don't filter the tasks with tracepoint filter, there may be lots of output. i.e. we always deploy lots of cgroup on a single host, but only some of them are important, while the others are not import. So we limit the not important cgroup to a low memory limit, and then the tasks in it may do frequent memcg reclaim, but we don't care. Thanks Yafang