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Thu, 17 Jul 2025 13:18:36 -0700 (PDT) MIME-Version: 1.0 References: <20250717082845.34673-1-jiahao.kernel@gmail.com> In-Reply-To: <20250717082845.34673-1-jiahao.kernel@gmail.com> From: Yuanchu Xie Date: Thu, 17 Jul 2025 13:18:20 -0700 X-Gm-Features: Ac12FXwtAKeMQOJbAIkHiXs4Kxx8yNT6FQ2wZ-vx_m9jtui3QP4tWcTFtOJXKgQ Message-ID: Subject: Re: [PATCH] mm/mglru: Update MG-LRU proactive reclaim statistics only to memcg To: Hao Jia Cc: akpm@linux-foundation.org, yuzhao@google.com, shakeel.butt@linux.dev, mhocko@kernel.org, lorenzo.stoakes@oracle.com, kinseyho@google.com, hannes@cmpxchg.org, gthelen@google.com, david@redhat.com, axelrasmussen@google.com, zhengqi.arch@bytedance.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Hao Jia Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Queue-Id: 703FA40010 X-Rspamd-Server: rspam06 X-Stat-Signature: ygr446sg1hmfn7uudjprj1faxfhoznfc X-HE-Tag: 1752783518-876608 X-HE-Meta: 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 7yY00hfa 7Hpo6tMft1gAnTUF/TGkd8X9K3msYqET1prEqLb7vT1Zk5yAPGoPq92BuBZjrgwTpF2GpQhYeCPG6aG/hl/cAY7oyjS6iAk1EZBnlmTdYDbVuH4aXXKIs/6+7nv7TOHMwgxSs2l/SgAGsqdJotjTIOPzFvSHvRoGEARwBq0G0aoYYvzHwQmHPgaox2/v7YW75YR+QLj0+rXFO68BvKMGumqYdAJb2BAcVy/hctBn9sr3iNsnjTQZuvyI8tVrlpE21AAsVM+dx8pZsjhsnuZIi5TWDoQy8bGvt/BViUKKsrS3oGLGAwFsNus/mhg== 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: List-Subscribe: List-Unsubscribe: Hi Hao, On Thu, Jul 17, 2025 at 1:29=E2=80=AFAM Hao Jia w= rote: > > From: Hao Jia > > Users can use /sys/kernel/debug/lru_gen to trigger proactive memory recla= im > of a specified memcg. Currently, statistics such as pgrefill, pgscan and > pgsteal will be updated to the /proc/vmstat system memory statistics. This is a debugfs interface and it's not meant for use in production or provide a stable ABI. Does memory.reclaim not work for your needs? I'm not against the change; I just hope you don't depend on it continuing to exist/behave a certain way. Shakeel's comment is accurate. The lru_gen interface uses the internal memcg id which is not usually used to interface with the userspace. Reading this file does show the cgroup path and memcg id association. > > This will confuse some system memory pressure monitoring tools, making > it difficult to determine whether pgscan and pgsteal are caused by > system-level pressure or by proactive memory reclaim of some specific > memory cgroup. > > Therefore, make this interface behave similarly to memory.reclaim. > Update proactive memory reclaim statistics only to its memory cgroup. > > Signed-off-by: Hao Jia The patch looks okay to me too. Thanks, Yuanchu