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b=krkTAbkPIIdY70Yq3zuaB9FSIdrTel4qNE3xdlDNjVLFwwxTGZMGP+7hylJJYWEcC WQy5X9zW0skQ1LsECxI/C6MsMaLBdvstxMaDWsxXRdGRpjDMtoF3d2p4dfCBbS8BZ/ 8mMzQQVvi4FkiP0YFwH5XQoF4dJJd8GnJRIJNmLY= Date: Wed, 12 Mar 2025 15:36:18 -0700 From: Andrew Morton To: Zhongkun He Cc: mhocko@suse.com, hannes@cmpxchg.org, muchun.song@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: vmscan: skip the file folios in proactive reclaim if swappiness is MAX Message-Id: <20250312153618.e24f399d2d9767ebef87519f@linux-foundation.org> In-Reply-To: <20250312094337.2296278-1-hezhongkun.hzk@bytedance.com> References: <20250312094337.2296278-1-hezhongkun.hzk@bytedance.com> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Queue-Id: 7548E1A0004 X-Stat-Signature: rdqju99s4h8gcyseog9ga4nyzr1qfamc X-Rspamd-Server: rspam06 X-HE-Tag: 1741818980-286291 X-HE-Meta: U2FsdGVkX1+4nZAOOd4iCe8jvWE1/LInlubtuwOu/EIIPbK7hBzJvEDy8CeF5vvIGwj65xwUX9UozUvzrHS3Kxky+vyEkTnksL79DKbgH09iiq/vkuIe4vJCC0PqiNrwNwlNi4LP4Aq1XTzj8qqogGuIBA+NkMbZfE+vUkS+/fjeJQvV0cxfNghI1m1ae+V9rju/+gzUMqH8MsQSIK2ufPZQoiIy8oCBlPf37xr5uQ3L1vkIk+8tB2AZ3PLUy2NPRU7367nvPRKo88WfhWh9L73VIYc/y5RtE4ILQrCoNiRMqUWeSAHNZvobGj+sSB2dolNBGQd4Udoob6F+dI+GRo7gPrH9g9xT/XtVUHUoP1ZvXuds9NPugcPUzyNx4IByuURuVwOAerdE2dEa1FOo2xyncHlcS2vkIjn/fF8NkHW73dSw3RGT7R7LZswNsqYfgZbVAJ2OMbWeFCPmQtJbWLzMcu4+Y1ISa3PW3phptijEIlR4su2TV7U5kfPST3zBazcSj6quhHlTH1Y6+sbOGFmm3hMN+8PYPy37aFePI1F8P2UynKkLXrfXnf5sAr46F/XA0Oh3NMBjyIKpUuP06sgUt3+DPMa1HVPooCCq1XWVDBw5K5JMVzq4zrrQwH/8vgOVI1/2TJGUq49yrDEV7aArlQ/Oh3R041A8EJDjsOH+SsqCmQbP0qxDrnJY7P7+4dsnImST75YC0+//9kIJhYJkff7QBjQb2p0cGrIPZt0ZhC5pB8BZdBATVZl2GtejR//MgjQk5wIUJIBCW3NWQYRDEGT5iVaKVggmXdOIocP/cRRepFYBXtWfAfT0/oUiBE4yLQFJZpZBTLp9ULIhkoCt1kEQ4gJde4cvz0j4AY8WOW2yFbm/f7KDq1lZluy6S0p78G4AK8BMkbhIFaIpNyx4qVCOzPeSBwAH9ueuJdNkmxcVLLKuVRVSrLIdoSu5rPROERMxRCa3Ju4q30e 1mNjtpLb hFIk/aa5GHh5sT+mAMu8VQQUIvXeGnSkH6yRRE3zHplpfEfqbcm8NF1ArvruJKcPYf9xhEhrsa04cQydzBkom50lUSWhtyh/l2yywLgh/z0PvfwY30WU8DL98XoOGNVG1mZMN3gS7b1BqTYIt7gK/IgalaVc7ZC6qCMZn7Wao8zTLT6X65TRHbRYSVt+L7vWWLBVkKPu6pUALN1Xl7IKDoCF/QjRsbWmSnKiKSThQjPEKCxDHj6JKREt2ryd33djAu6I7jD6wlGw8Mi4= 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 Wed, 12 Mar 2025 17:43:37 +0800 Zhongkun He wrote: > With this patch 'commit <68cd9050d871> ("mm: add swappiness= arg to > memory.reclaim")', we can submit an additional swappiness= argument > to memory.reclaim. It is very useful because we can dynamically adjust > the reclamation ratio based on the anonymous folios and file folios of > each cgroup. For example,when swappiness is set to 0, we only reclaim > from file pages. > > However,we have also encountered a new issue: when swappiness is set to > the MAX_SWAPPINESS, it may still only reclaim file folios. This is due > to the knob of cache_trim_mode, which depends solely on the ratio of > inactive folios, regardless of whether there are a large number of cold > folios in anonymous folio list. > > So, we hope to add a new control logic where proactive memory reclaim only > reclaims from anonymous folios when swappiness is set to MAX_SWAPPINESS. > For example, something like this: > > echo "2M swappiness=200" > /sys/fs/cgroup/memory.reclaim > > will perform reclaim on the rootcg with a swappiness setting of 200 (max > swappiness) regardless of the file folios. Users have a more comprehensive > view of the application's memory distribution because there are many > metrics available. > > With this patch, the swappiness argument of memory.reclaim has a more > precise semantics: 0 means reclaiming only from file pages, while 200 > means reclaiming just from anonymous pages. Please update Documentation/admin-guide/cgroup-v2.rst for this.