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Thu, 20 Apr 2023 11:57:17 -0700 (PDT) MIME-Version: 1.0 References: <20230403220337.443510-1-yosryahmed@google.com> <20230403220337.443510-4-yosryahmed@google.com> In-Reply-To: <20230403220337.443510-4-yosryahmed@google.com> From: Shakeel Butt Date: Thu, 20 Apr 2023 11:57:06 -0700 Message-ID: Subject: Re: [PATCH mm-unstable RFC 3/5] memcg: calculate root usage from global state To: Yosry Ahmed Cc: Alexander Viro , Christian Brauner , Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , Andrew Morton , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: C9BABC001C X-Rspam-User: X-Stat-Signature: jiabsfoe4k7dd551s8xfxw8qe1pd773z X-HE-Tag: 1682017038-550799 X-HE-Meta: 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 /Na9N9RI Eb0kkoUiS9AivcqRmupQpyDthzy9zNlqK/CAPf5F9lJoZdSQ8tSy/kwZYaCsl2JWdWWX39bkwC2L5DWMFFuhN155zrx8rZvMpa/qDys2O8T12Ppa77HcFRHPVuYfnf4ChM43szEZKp98381UqzMTMTzU0Z/YBXJdwPYDg8ugYZWptw17KqY16ruN/QYLb4zIVNiat57UsC+pIpK0oSIV4lO4bvFMrVt0zuPwxKkmunxexs/bGKXiODSzkDD+GvMHBJ9o/V6aI38ZNujPesV2AH3ntJg== 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 Mon, Apr 3, 2023 at 3:03=E2=80=AFPM Yosry Ahmed = wrote: > > Currently, we approximate the root usage by adding the memcg stats for > anon, file, and conditionally swap (for memsw). To read the memcg stats > we need to invoke an rstat flush. rstat flushes can be expensive, they > scale with the number of cpus and cgroups on the system. > > mem_cgroup_usage() is called by memcg_events()->mem_cgroup_threshold() > with irqs disabled, so such an expensive operation with irqs disabled > can cause problems. > > Instead, approximate the root usage from global state. This is not 100% > accurate, but the root usage has always been ill-defined anyway. > > Signed-off-by: Yosry Ahmed Acked-by: Shakeel Butt