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([138.199.21.246]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-84564d6c2cesm11059604b3a.2.2026.06.22.21.36.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 22 Jun 2026 21:36:46 -0700 (PDT) From: Jing Wu To: Thomas Gleixner Cc: Jing Wu , Waiman Long , linux-kernel@vger.kernel.org, rcu@vger.kernel.org, cgroups@vger.kernel.org, Qiliang Yuan Subject: Re: [PATCH v3 08/13] genirq: Add explicit housekeeping callback for managed IRQ migration Date: Tue, 23 Jun 2026 12:36:41 +0800 Message-ID: <20260623043641.2391662-1-realwujing@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <87cxxnegqa.ffs@fw13> References: <87cxxnegqa.ffs@fw13> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On Thu, Jun 18 2026 at 22:27, Thomas Gleixner wrote: > While this series might work for you by some definition of "works", > it's broken beyond repair [...] > Please coordinate with Waiman or whoever is working on it at RH right now. Thank you for the detailed review. I want to clarify the timeline and highlight a key distinction before proceeding with v4. DHM was posted as RFC on 2026-02-06 [1], v1 on 2026-03-25 [2], and v2 on 2026-04-13 [3]. Waiman Long's series was posted on 2026-04-20 [4], seven days after DHM v2. The development appears to have been parallel. More importantly, DHM and Waiman's series differ in a key requirement: Waiman's series requires "nohz_full=" to be present at boot (even with an empty CPU list) to opt into runtime updates. DHM's goal is to enable CPU noise isolation at runtime on systems where no nohz_full= was configured at boot — a use case his series does not cover. That said, I fully accept the architectural feedback: the on-the-fly subsystem modification approach in v3 is wrong, and v4 should use the CPU hotplug machinery. We are open to coordinating with Waiman on a unified approach that covers both use cases. Before starting v4, two questions: 1. Is the "no boot parameter required" use case worth pursuing independently, or should it be folded into Waiman's series? 2. For the hotplug path: is CPU-by-CPU offline/online the expected mechanism, given that you rejected the cpuhp_offline_cb() bulk approach in Waiman's v1? [1] https://lore.kernel.org/r/20260206-feature-dynamic_isolcpus_dhei-v1-0-00a711eb0c74@gmail.com [2] https://lore.kernel.org/r/20260325-dhei-v12-final-v1-0-919cca23cadf@gmail.com [3] https://lore.kernel.org/r/20260413-wujing-dhm-v2-0-06df21caba5d@gmail.com [4] https://lore.kernel.org/r/20260421030351.281436-1-longman@redhat.com Jing Wu