From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id E5C33C433F5 for ; Fri, 6 May 2022 15:05:13 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 4294D6B0072; Fri, 6 May 2022 11:05:13 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 3D9616B0073; Fri, 6 May 2022 11:05:13 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2A1A16B0074; Fri, 6 May 2022 11:05:13 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0026.hostedemail.com [216.40.44.26]) by kanga.kvack.org (Postfix) with ESMTP id 1CDED6B0072 for ; Fri, 6 May 2022 11:05:13 -0400 (EDT) Received: from smtpin25.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id D394EA6311 for ; Fri, 6 May 2022 15:05:12 +0000 (UTC) X-FDA: 79435641264.25.0169D27 Received: from mail-io1-f47.google.com (mail-io1-f47.google.com [209.85.166.47]) by imf26.hostedemail.com (Postfix) with ESMTP id 0B1A1140044 for ; Fri, 6 May 2022 15:05:09 +0000 (UTC) Received: by mail-io1-f47.google.com with SMTP id z18so8349860iob.5 for ; Fri, 06 May 2022 08:05:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=arista.com; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=2LpI0DImiuDC2UzRqfJHQ2qAza8P08IbEZJSnDfETww=; b=C3DmY9zqQpuSybTFOak9V+J6u4wDYDHiArS7riORo4yB6KdqsWLxhsWFUXdp5Zs75r KlULlrzTb6vVdS+TmD/jo/bV8PW3aZ5GW7HeytlG87S0bd1BJT21JxJdPWnjs0hSF3SU zV/hZEYf+9AtoPpN49UXruQAhUzGe606FESKKBMPigXxbhAw9OFDNrCDZXxjxGJZYD/A VBaa9IqZP05rI4wxT6MUkVDoNQOipok6hfIKKdi9UVogn/sEkGZSRfzgP16cJnQki1Il D8XmaVr2p3CeL/fFfwnlhIqGTkcSaaLAssco5zlEM4tyNawoaqQiJXtR6lcRyYHVaZPU +lbw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=2LpI0DImiuDC2UzRqfJHQ2qAza8P08IbEZJSnDfETww=; b=t58iai/U36fIt97SN7fu4hK5AR9RuR0H58mIxbfoNUf9rscYemgrtntZeYZLzpiTcs um2WOIMn4QWS9NFRXyataqm3xi9sGLMwxAaAo+ixB3QJ+9p6bBuz2MviY5mImveVZq8P Jee3QijErVrpwgs4eXW6lJ+Wp42iWuHlGWLGeNaK0ijRmImQVOm6KQ7+roG7eLW3ht2v +xvhExCLg0QHRovfVXNihfLUK0oFYjaSdpIq0ejcds0VSQiU6zFflFyGgNRM8I3Rb7I5 8vLbKPejiC/anV0uUpfVP/4uVShunE5wp096l2rBwzQDRelKyOjsVyBBmkGjaIkpIqEu rl/A== X-Gm-Message-State: AOAM53233ToKgcLUffYZfJsW/zwTRGMr4aoPki3dtzle+6GriV2i9hCK eGodQETnN/bXuyQtoKOKqoPdt4IJZHKNEPBFqQf2tg== X-Google-Smtp-Source: ABdhPJxeb79WtbUmSsuNP/GjVqnX8MbYvhajHJu6C3ecnqMNPy2jQSs2AQGuAJ8tlrZ+czv/9fyK+O6wejD/c8fhKsg= X-Received: by 2002:a05:6638:140d:b0:32b:c643:e334 with SMTP id k13-20020a056638140d00b0032bc643e334mr1250057jad.125.1651849511454; Fri, 06 May 2022 08:05:11 -0700 (PDT) MIME-Version: 1.0 References: <20220505121329.GA32827@us192.sjc.aristanetworks.com> In-Reply-To: From: Ganesan Rajagopal Date: Fri, 6 May 2022 20:34:34 +0530 Message-ID: Subject: Re: [PATCH] mm/memcontrol: Export memcg->watermark via sysfs for v2 memcg To: Johannes Weiner Cc: mhocko@kernel.org, roman.gushchin@linux.dev, shakeelb@google.com, cgroups@vger.kernel.org, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: 0B1A1140044 X-Stat-Signature: 8aezwbuz15p3nmgi7hui9sk8ubjdgu7c Authentication-Results: imf26.hostedemail.com; dkim=pass header.d=arista.com header.s=google header.b=C3DmY9zq; dmarc=pass (policy=reject) header.from=arista.com; spf=none (imf26.hostedemail.com: domain of rganesan@arista.com has no SPF policy when checking 209.85.166.47) smtp.mailfrom=rganesan@arista.com X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1651849509-902720 X-Bogosity: Ham, tests=bogofilter, spamicity=0.082821, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, May 6, 2022 at 8:27 PM Johannes Weiner wrote: > > On Thu, May 05, 2022 at 05:13:30AM -0700, Ganesan Rajagopal wrote: > > v1 memcg exports memcg->watermark as "memory.mem_usage_in_bytes" in > > sysfs. This is missing for v2 memcg though "memory.current" is exported. > > There is no other easy way of getting this information in Linux. > > getrsuage() returns ru_maxrss but that's the max RSS of a single process > > instead of the aggregated max RSS of all the processes. Hence, expose > > memcg->watermark as "memory.watermark" for v2 memcg. > > > > Signed-off-by: Ganesan Rajagopal > > This wasn't initially added to cgroup2 because its usefulness is very > specific: it's (mostly) useless on limited cgroups, on long-running > cgroups, and on cgroups that are recycled for multiple jobs. And I > expect these categories apply to the majority of cgroup usecases. > > However, for the situation where you want to measure the footprint of > a short-lived, unlimited one-off cgroup, there really is no good > alternative. And it's a legitimate usecase. It doesn't cost much to > maintain this info. So I think we should go ahead with this patch. > > But please add a blurb to Documentation/admin-guide/cgroup-v2.rst. Thank you for the review. I'll refresh the patch with the documentation blurb. Ganesan