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Wed, 4 Sep 2024 14:49:21 +0800 Message-ID: Date: Wed, 4 Sep 2024 14:49:20 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird CC: , , , , , , , , Subject: Re: [PATCH] mm, proc: collect percpu free pages into the free pages Content-Language: en-US To: References: <20240830014453.3070909-1-mawupeng1@huawei.com> <87a5guh2fb.fsf@yhuang6-desk2.ccr.corp.intel.com> <2ee7cb17-9003-482c-9741-f1f51f61ab4b@huawei.com> <871q22hmga.fsf@yhuang6-desk2.ccr.corp.intel.com> <193da117-30b8-425a-b095-6fd8aca1c987@huawei.com> From: mawupeng In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.178.120] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To kwepemg100017.china.huawei.com (7.202.181.58) X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 7582B40006 X-Stat-Signature: idmrtqr5ysb9wdn1ikjqwx17afrsz99w X-HE-Tag: 1725432566-665171 X-HE-Meta: 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 Nrh/1LhU FM4uW5FhvCp8GzIrraNyMyH7mxKxKOM6XJJ74LsNAOthGmhLfyPfGYPseD1G83uuCpcJrOgS0hIULIJ2PJGj0gLX7Iv0wuPFaQ6YZvUURATj/E7U666GSfCx1BVL7ZvvV/TE9d+VDmuadVZBEQozu+cyM6XL01IalNvrluARSjqIvfIYi3rOAv/Ncr5+GaecrSFOwtjb6IpPNEG5DJul8LURm3w== 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: On 2024/9/3 16:09, Michal Hocko wrote: > On Tue 03-09-24 09:50:48, mawupeng wrote: >>> Drain remote PCP may be not that expensive now after commit 4b23a68f9536 >>> ("mm/page_alloc: protect PCP lists with a spinlock"). No IPI is needed >>> to drain the remote PCP. >> >> This looks really great, we can think a way to drop pcp before goto slowpath >> before swap. > > We currently drain after first unsuccessful direct reclaim run. Is that > insufficient? The reason i said the drain of pcp is insufficient or expensive is based on you comment[1] :-）. Since IPIs is not requiered since commit 4b23a68f9536 ("mm/page_alloc: protect PCP lists with a spinlock"). This could be much better. [1]: https://lore.kernel.org/linux-mm/ZWRYZmulV0B-Jv3k@tiehlicka/ > Should we do a less aggressive draining sooner? Ideally > restricted to cpus on the same NUMA node maybe? Do you have any specific > workloads that would benefit from this? Current the problem is amount the pcp, which can increase to 4.6%(24644M) of the total 512G memory.