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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 Message-ID: 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 In-Reply-To: <20261103075940.110308-5-matthew.ruffell@canonical.com> X-Rspamd-Server: rspam06 X-Stat-Signature: dpg9s8m5p3yc76wmn6wckwapbx6d6atz X-Spam-Status: No, score=-10.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-Rspamd-Queue-Id: 9F369C000C X-Rspam-User: X-HE-Tag: 1793715026-874252 X-HE-Meta: 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 T3kdUrLO 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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 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? Thanks. -- Frederic Weisbecker SUSE Labs