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[209.85.220.65]) by mx.google.com with SMTPS id y127sor8624659wmd.1.2019.07.06.04.26.18 for (Google Transport Security); Sat, 06 Jul 2019 04:26:18 -0700 (PDT) Received-SPF: pass (google.com: domain of chris@chrisdown.name designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@chrisdown.name header.s=google header.b=tAKMZiRf; spf=pass (google.com: domain of chris@chrisdown.name designates 209.85.220.65 as permitted sender) smtp.mailfrom=chris@chrisdown.name; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=chrisdown.name DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chrisdown.name; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=OM49BpAdnzvrpDwsLEkj6E8wRKIUTEsST/MpMEgc2Jc=; b=tAKMZiRfwWQp/kay69XYGdCwDCqfLH0TrI/wVedRt+GsmZ+ILfOxq168JyrsF5snL2 xukFIZ4bOA3qgF3BqeyEeFAySnREtioo3Q6UTKXYWLNjLyeGfz/rwXqmki7XdW1SmnxV W3MHFsiMUHek/x8Ux5Ycq2cZC/+tnkHjaO5Eg= X-Google-Smtp-Source: APXvYqxjsq2xUCkUaCNFHghtwPdwf3b/8E45ZDom/BLRGstJS7F1QzoD5Z3AohrxnUt6TLQApcTLIQ== X-Received: by 2002:a1c:dc07:: with SMTP id t7mr8225563wmg.164.1562412377886; Sat, 06 Jul 2019 04:26:17 -0700 (PDT) Received: from localhost ([2a01:4b00:8432:8a00:56e1:adff:fe3f:49ed]) by smtp.gmail.com with ESMTPSA id 91sm5502444wrp.3.2019.07.06.04.26.13 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Sat, 06 Jul 2019 04:26:16 -0700 (PDT) Date: Sat, 6 Jul 2019 12:26:12 +0100 From: Chris Down To: Yafang Shao Cc: Michal Hocko , Andrew Morton , Linux MM , Johannes Weiner , Vladimir Davydov , Shakeel Butt , Yafang Shao Subject: Re: [PATCH] mm, memcg: support memory.{min, low} protection in cgroup v1 Message-ID: <20190706112612.GA20696@chrisdown.name> References: <1562310330-16074-1-git-send-email-laoar.shao@gmail.com> <20190705090902.GF8231@dhcp22.suse.cz> <20190705155239.GA18699@chrisdown.name> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.12.1 (2019-06-15) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000100, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Yafang Shao writes: >> While it may superficially work without it, I'm sceptical that simply adding >> memory.low and memory.min to the v1 hierarchy is going to end up with >> reasonable results under scrutiny, or a coherent system or API. > >I have finished some simple stress tests, and the result are fine. >Would you pls give me some suggestion on how to test it if you think >there may be some issues ? My concerns are about introducing an API that requires propagation of control into an API that doesn't delineate between using values for *propagation* and using values for *consumption*, and this becomes significantly more important when we're talking about something that necessitates active propagation of values like memory.{low,min}. That's one reason why I bring up concerns related to the fact that v1 allows processes in intermediate cgroups. So again, I'm not expecting that anything necessarily technically goes wrong (hence my comment at the beginning), just that it doesn't necessarily compose to a reasonable thing to have in v1. My concerns are almost strictly about exposing this as an interface in an API that doesn't have qualities that make the end result reasonable.