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b=Cei6t3wurYvcqLQ8H2fXgzvGtE6cRpVUyA8AffmgjAgAOfEYxygt4RCJBrALcO0Sp tKa+a1VDEYYmBjjAScghRMc/j+hfnzXgjc/dymeTtOzywRMRjf9jlxXl1o4SETCQw8 nNa4ju2UOa82u21K1nS7yiqkywpr4ZHrbThOOBqw= Date: Mon, 9 Sep 2024 15:22:15 -0700 From: Andrew Morton To: Hailong Liu Cc: Barry Song <21cnbao@gmail.com>, Lokesh Gidra , Suren Baghdasaryan , Nicolas Geoffray , Michal Hocko , gaoxu , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , Shaohua Li , yipengxiang , fengbaopeng , Kalesh Singh Subject: Re: [PATCH v2] mm: add lazyfree folio to lru tail Message-Id: <20240909152215.31e85028c4d09681f09e7509@linux-foundation.org> In-Reply-To: <20240827022911.bcje3ofucegg6vjl@oppo.com> References: <20240827021351.iq6i7zkwm32xili3@oppo.com> <20240827022911.bcje3ofucegg6vjl@oppo.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: DE8B620011 X-Stat-Signature: 8q4kmpafemi3xagzs8opiye4y43c6uks X-HE-Tag: 1725920537-72754 X-HE-Meta: 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 fIVIN/5e tuEm7r1NNmEZkCmD1Ux8rGYxF7TTxCJ/3s22Hq3dBl0zNftH79ycbK4+XIcGV+HbnwbA0fffNhZJ8fyNi0uUTGbYXYdmBWOzsx6ubIiQ7CLxOru4YZOUfNyHcswbzAvfLz81HWiFF/fgLCnsEBb+pROQjT+AihkeSpsIj+Woa2RjPbx8LBPDM2GxKJB8j83iULB+1U+JOUjOlPSpEpedsbYL3jAROs1l3/we+/b/8y3ypCPr4usn7er8+bJ5T48XSEZUNoCxzIH2f25Ecr8/c1lzPINNMKNBeD4Ioz6nDHx9SgjdupaYZQpQ4vK7zwEr12SeAhEqOIDCtFr4YomaWWNMqAw== 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 Tue, 27 Aug 2024 10:29:11 +0800 Hailong Liu wrote: > On Tue, 27. Aug 14:18, Barry Song wrote: > > On Tue, Aug 27, 2024 at 2:13 PM Hailong Liu wrote: > > > > > > On Mon, 26. Aug 09:37, Lokesh Gidra wrote: > > > > > > > > IMHO, within LRU_INACTIVE_FILE, MADV_FREE'ed pages should be > > > > prioritized for reclamation over file ones. > > > > > > > > > > > > > > > > Adding Lokesh. > > > > > Lokesh, could you please comment on the reasoning behind the above > > > > > mentioned change? > > > > > > > > Adding Nicolas as well, in case he wants to add something. > > > IMHO, lruvec_add_folio is enough. if lruvec_add_folio_tail why not use > > > MADV_DONTNEED instead? In MM the reclaim policy prefer to reclaim file cache, if > > > MADV_FREE'd pages directly add to the tail, they might be reclaimed instantly. > > > Also the benefit of workingset_refault_file cannot be convinced for me. > > > > My understanding is that MADV_DONTNEED will immediately free the memory, > > whereas MADV_FREE will release memory only under memory pressure. If > > memory pressure is low, the anonymous memory may still be gotten back > > without causing page faults. This might be what Lokesh is aiming to achieve. > > > Hmm, IIUC, for the reason of watermark, the kswapd would do reclamation without > memory pressure. I worried here is that the madv_free'd pages reclaimed too fast > if add to tail. I'm not seeing much clarity on whether we should merge this change. I think I'll drop this version - let's please revisit after -rc1.