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Wed, 05 Apr 2023 11:56:29 -0700 (PDT) MIME-Version: 1.0 References: <20230404001353.468224-1-yosryahmed@google.com> <20230404143824.a8c57452f04929da225a17d0@linux-foundation.org> <20230404145830.b34afedb427921de2f0e2426@linux-foundation.org> <20230404152816.cec6d41bfb9de4680ae8c787@linux-foundation.org> <20230404153124.b0fa5074cf9fc3b9925e8000@linux-foundation.org> <20230405114841.248dffb65526383823c71d60@linux-foundation.org> In-Reply-To: <20230405114841.248dffb65526383823c71d60@linux-foundation.org> From: Yosry Ahmed Date: Wed, 5 Apr 2023 11:55:53 -0700 Message-ID: Subject: Re: [PATCH v4 0/3] Ignore non-LRU-based reclaim in memcg reclaim To: Andrew Morton Cc: Alexander Viro , "Darrick J. Wong" , Christoph Lameter , David Rientjes , Joonsoo Kim , Vlastimil Babka , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, "Matthew Wilcox (Oracle)" , Miaohe Lin , David Hildenbrand , Johannes Weiner , Peter Xu , NeilBrown , Shakeel Butt , Michal Hocko , Yu Zhao , Dave Chinner , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Queue-Id: BFDBE1C001E X-Rspamd-Server: rspam01 X-Stat-Signature: tdnxj6ngdwxao86es8cto1j4ejofqaac X-HE-Tag: 1680720991-473984 X-HE-Meta: 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 hITb9Zbo qM6FBHqlbjuagy9h3YlIE5u/riE0HsUUy9bYpGnldW1XSsYEsXX5jXfoJ+qOX4PVrPp0TZrVguyNOdj2ac/KSkza9hjjbOxF8Z0Tp/Wx2/qG2Q+N4QwI67oQqUWulAZNIaPdgP0zFPFhDG8ZG9Zcvvt+cy/agIEAHmzblQUqcV0H7FcWcCwfxOAio2+Og0fuS7nu8QM5obyqj05sKWFqFiBZ43meqch+ixwHykvu5NQ46n71cFT5HcxkChM4zyN5D85hdyWhvc+xWjP9q/45ASoHGPpuA/tAPLpC1C6DLZpyTF72nU3liSMktcy24c2OWstljGFcowuQ1nfKcNRtNUrwrkYxMyfZ2wuJ3MsHpSLj+Ad6+6Gm1vHUITKBHmJGGk7X5l3f7E5UCu2nzQ1iQOpmuhsVMOV5/Dun3hGMEj/SoqNI4Ihpuczp6kso0glbmW6yVLbBTvZe8o80= 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 Wed, Apr 5, 2023 at 11:48=E2=80=AFAM Andrew Morton wrote: > > On Tue, 4 Apr 2023 16:46:30 -0700 Yosry Ahmed wro= te: > > > > But the key question remains: how desirable is a backport? > > > > > > Looking at the changelogs I'm not seeing a clear statement of the > > > impact upon real-world users' real-world workloads. (This is a hint)= . > > > So I am unable to judge. > > > > > > Please share your thoughts on this. > > > > I think it's nice to have but not really important. It occasionally > > causes writes to memory.reclaim to report false positives and *might* > > cause unnecessary retrying when charging memory, but probably too rare > > to be a practical problem. > > > > Personally, I intend to backport to our kernel at Google because it's > > a simple enough fix and we have occasionally seen test flakiness > > without it. > > > > I have a reworked version of the series that only has 2 patches: > > - simple-two-liner-patch (actually 5 lines) > > - one patch including all refactoring squashed (introducing > > flush_reclaim_state() with the huge comment, introducing > > mm_account_reclaimed_pages(), and moving set_task_reclaim_state() > > around). > > > > Let me know if you want me to send it as v5, or leave the current v4 > > if you think backporting is not generally important. > > Let's have a look at that v5 and see what people think? Sent v5 [1]. Thanks Andrew! [1]https://lore.kernel.org/lkml/20230405185427.1246289-1-yosryahmed@google.= com/