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Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato , Brendan Jackman , Johannes Weiner , Zi Yan , Harry Yoo , Hao Li , Christoph Lameter , David Rientjes , Roman Gushchin , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Barry Song , Youngjun Park , Qi Zheng , Shakeel Butt , Axel Rasmussen , Yuanchu Xie , Wei Xu , "Borislav Petkov (AMD)" , Randy Dunlap , Thomas Gleixner , Feng Tang , Dapeng Mi , Kees Cook , Marco Elver , Jakub Kicinski , Li RongQing , Eric Biggers , "Paul E. McKenney" , Nathan Chancellor , Miguel Ojeda , Nicolas Schier , Thomas =?utf-8?Q?Wei=C3=9Fschuh?= , Douglas Anderson , Gary Guo , Christian Brauner , Pasha Tatashin , Masahiro Yamada , Coiby Xu , Frederic Weisbecker , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-rt-devel@lists.linux.dev Subject: Re: [PATCH v4 0/4] Introduce Per-CPU Work helpers (was QPW) Message-ID: <20260714101248.hV06z2cr@linutronix.de> References: <20260519012754.240804-1-leobras.c@gmail.com> <20260520130903.Ebsd4aUa@linutronix.de> <20260713080723.XOTiibfG@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 867461C0004 X-Stat-Signature: m857mjxxeppki339kzh1ysfgfcsft7s4 X-HE-Tag: 1784023972-216195 X-HE-Meta: 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 4YzGSETG coXV04FfiJiET9/GxUIog9cd9znIqkoxPTL8k4RijAvaiH6yBbec96e7oxsxp9GD9XvxlMn8W/aEcIQewRdPv3t3nFSL9+0QOhxYS06x5XnSKqe/nw8/ubSIfuwYoV/iCHNTfhH5M89108IOf5TrVscqmQ46hnMINamo1c/0afjEUBtcyUeAwAb8fdirpsDPFQ2VxRJonCTsr7X+zbJYR39MGY3Agzu+SEJas/owtQZAWep080ZmqZlvsEAZO+7Y6lrsvFNAqbko3UJs= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2026-07-13 18:17:23 [-0300], Leonardo Bras wrote: > IIRC there are multiple users of this mechanism around the kernel. I > remember picking the first three (swap, slub and memcontrol) as examples of > how to use pwlocks (QPW at the time). With the concept proven, I could then > proceed to work with other potential users to replace it. (We ended up > dropping memcontrol in the process) > > The main idea is to replace as many potential users as possible to reduce > as much as possible the amount of IPIs in isolated cpus, and allow Linux > to run workloads which require much lower latency. Right. I am not entirely opposed to this idea. If you can't improve the situation by other means I would consider this as the last resort. If the mm folks are on board with this, then even better. > This idea came as a general solution to a bunch of latency violations > Marcelo and I were coming across. > > Thanks! > Leo Sebastian