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[98.15.154.102]) by smtp.gmail.com with ESMTPSA id f19-20020a05620a409300b00680c933fb1csm2254822qko.20.2022.04.01.14.13.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 01 Apr 2022 14:13:52 -0700 (PDT) Date: Fri, 1 Apr 2022 17:13:52 -0400 From: Johannes Weiner To: Roman Gushchin Cc: Yosry Ahmed , Michal Hocko , Shakeel Butt , Andrew Morton , David Rientjes , Tejun Heo , Zefan Li , cgroups@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Linux-MM , Jonathan Corbet , Yu Zhao , Dave Hansen , Wei Xu , Greg Thelen Subject: Re: [PATCH resend] memcg: introduce per-memcg reclaim interface Message-ID: References: <20220331084151.2600229-1-yosryahmed@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: hna31yt78jk9oajwnmpz6dxwtcse5hw1 X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 225A040046 Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=cmpxchg-org.20210112.gappssmtp.com header.s=20210112 header.b=S3e9r2h5; dmarc=pass (policy=none) header.from=cmpxchg.org; spf=pass (imf04.hostedemail.com: domain of hannes@cmpxchg.org designates 209.85.222.180 as permitted sender) smtp.mailfrom=hannes@cmpxchg.org X-Rspam-User: X-HE-Tag: 1648847634-358936 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 Fri, Apr 01, 2022 at 11:39:30AM -0700, Roman Gushchin wrote: > The interface you're proposing is not really extensible, so we'll likely need to > introduce a new interface like memory.reclaim_ext very soon. Why not create > an extensible API from scratch? > > I'm looking at cgroup v2 documentation which describes various interface files > formats and it seems like given the number of potential optional arguments > the best option is nested keyed (please, refer to the Interface Files section). > > E.g. the format can be: > echo "1G type=file nodemask=1-2 timeout=30s" > memory.reclaim Yeah, that syntax looks perfect. But why do you think it's not extensible from the current patch? We can add those arguments one by one as we agree on them, and return -EINVAL if somebody passes an unknown parameter. It seems to me the current proposal is forward-compatible that way (with the current set of keyword pararms being the empty set :-))