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[209.85.220.65]) by mx.google.com with SMTPS id v191sor354940ywe.185.2019.01.30.09.07.02 for (Google Transport Security); Wed, 30 Jan 2019 09:07:02 -0800 (PST) Received-SPF: pass (google.com: domain of htejun@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=rQjmckmz; spf=pass (google.com: domain of htejun@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=htejun@gmail.com; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=r4FvnOpw+Kp/xo1E/oIUXzj02pZKaUP0vrX/v1MVF3s=; b=rQjmckmzAv1TtgaDTf+xwGnxDCZf/qt62fsajJvyFlBof5l/0CVKAG0/RQdHbYUU8Z YV3pupMl9wakI8GJ2a6Q6X1czRWRbqRIrvDYdBGenYJH/AT+DrU6hAeWiAJeKafhh47f jEDi7+H+xXmSLP+84wuhC/kTT1At/AlXUGMc7YbhpX92ShXurAJwHvoI1VXRc8cN2NoO uMKjdB5EwWa9+9c0xWSBmyKrQBV0LdzTOgzkmuI9iU0gbxpf1N+yxqips6zJE2ehg/yz 2hltgR4GXOpilyhCa+c/RA4A40XOj85aph8KTQMtFbCHYe82rL28IeBb2qbM1WjpktGs JPnQ== X-Google-Smtp-Source: ALg8bN46/CyjNniPd/uEyCmyWWAS1mahMjoWkazGoUDEhY78foz8Nqb7qCmY2P58ISnLM36C8mVYug== X-Received: by 2002:a81:3413:: with SMTP id b19mr29798236ywa.297.1548868021695; Wed, 30 Jan 2019 09:07:01 -0800 (PST) Received: from localhost ([2620:10d:c091:200::7:e55d]) by smtp.gmail.com with ESMTPSA id g84sm2015945ywg.9.2019.01.30.09.07.00 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 30 Jan 2019 09:07:00 -0800 (PST) Date: Wed, 30 Jan 2019 09:06:58 -0800 From: Tejun Heo To: Michal Hocko Cc: Johannes Weiner , Chris Down , Andrew Morton , Roman Gushchin , Dennis Zhou , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, kernel-team@fb.com Subject: Re: [PATCH 2/2] mm: Consider subtrees in memory.events Message-ID: <20190130170658.GY50184@devbig004.ftw2.facebook.com> References: <20190128142816.GM50184@devbig004.ftw2.facebook.com> <20190128145210.GM18811@dhcp22.suse.cz> <20190128145407.GP50184@devbig004.ftw2.facebook.com> <20190128151859.GO18811@dhcp22.suse.cz> <20190128154150.GQ50184@devbig004.ftw2.facebook.com> <20190128170526.GQ18811@dhcp22.suse.cz> <20190128174905.GU50184@devbig004.ftw2.facebook.com> <20190129144306.GO18811@dhcp22.suse.cz> <20190129145240.GX50184@devbig004.ftw2.facebook.com> <20190130165058.GA18811@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190130165058.GA18811@dhcp22.suse.cz> User-Agent: Mutt/1.5.21 (2010-09-15) 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: Hello, Michal. On Wed, Jan 30, 2019 at 05:50:58PM +0100, Michal Hocko wrote: > > Yeah, cgroup.events and .stat files as some of the local stats would > > be useful too, so if we don't flip memory.events we'll end up with sth > > like cgroup.events.local, memory.events.tree and memory.stats.local, > > which is gonna be hilarious. > > Why cannot we simply have memory.events_tree and be done with it? Sure > the file names are not goin to be consistent which is a minus but that > ship has already sailed some time ago. Because the overall cost of shitty interface will be way higher in the longer term. cgroup2 interface is far from perfect but is way better than cgroup1 especially for the memory controller. Why do you think that is? > > If you aren't willing to change your mind, the only option seems to be > > introducing a mount option to gate the flip and additions of local > > files. Most likely, userspace will enable the option by default > > everywhere, so the end result will be exactly the same but I guess > > it'll better address your concern. > > How does the consumer of the API learns about the mount type? It's gonna be a mount flag exposed in /sys/kernel/cgroup/features. Thanks. -- tejun