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Wed, 04 Nov 2026 16:38:52 -0800 (PST) Received: from WindFlash.powerhub ([2a0a:ef40:f61:3b01:d08a:833b:756:8fce]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-48fed553441sm5988761f8f.43.2026.11.04.16.38.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Nov 2026 16:38:51 -0800 (PST) From: Leonardo Bras To: Frederic Weisbecker Cc: Leonardo Bras , Matthew Ruffell , Waiman Long , Tejun Heo , Peter Zijlstra , Ingo Molnar , Andrew Morton , David Hildenbrand , Caron Wills , Ridong Chen , Johannes Weiner , Michal =?iso-8859-1?Q?Koutn=FD?= , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , K Prateek Nayak , Lorenzo Stoakes , "Liam R . Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, Jay Vosburgh Subject: Re: [PATCH 4/6] sched/isolation: Drain per-CPU LRU batches when CPUs become isolated Date: Wed, 4 Nov 2026 21:38:50 -0300 Message-ID: X-Mailer: git-send-email 2.55.0 In-Reply-To: References: <20261103075940.110308-1-matthew.ruffell@canonical.com> <20261103075940.110308-5-matthew.ruffell@canonical.com> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-9.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FORGED_GMAIL_RCVD,FREEMAIL_FORGED_FROMDOMAIN, FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=4.0.1 X-Rspamd-Server: rspam09 X-Stat-Signature: 3sqfyxzahr3epc9upq36si95bgpppem7 X-Rspamd-Queue-Id: D04A9140005 X-Rspam-User: X-HE-Tag: 1793839133-887061 X-HE-Meta: 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 h0FBRtbi 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Tue, Nov 03, 2026 at 03:10:22PM +0100, Frederic Weisbecker wrote: > Le Tue, Nov 03, 2026 at 08:59:38PM +1300, Matthew Ruffell a écrit : > > From: Caron Wills > > > > Isolated CPUs no longer batch folios in their per-CPU LRU caches, so > > that __lru_add_drain_all() never has to queue work on them. Boot time > > isolation (isolcpus=, nohz_full=) takes effect before any folio is > > batched, but a cpuset isolated partition can be created at runtime and > > the affected CPUs may still hold folios in their batches from before. > > Those would linger until the CPU happens to drain locally, and the next > > lru_add_drain_all() would fall back to queueing work on the now isolated > > CPU, which is exactly what must be avoided. > > > > Drain all batches once from housekeeping_update(), right after the > > HK_TYPE_DOMAIN mask has been updated and next to the vmstat and memcg > > workqueue flushes that exist for the same reason, so that newly isolated > > CPUs start out with empty batches. > > > > Link: https://bugs.launchpad.net/bugs/2165410 > > Signed-off-by: Caron Wills > > Signed-off-by: Matthew Ruffell > > There was this patchset: > https://lore.kernel.org/lkml/20260519012754.240804-1-leobras.c@gmail.com/ > > Leonardo, do you plan a v5? Yeah, working on that. Hopefully should be tested by the end of this month. Thanks! Leo