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([2601:188:c102:b180:1f8b:71d0:77b1:1f6e]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-4ed64f14f93sm3224961cf.26.2025.11.03.19.42.06 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 03 Nov 2025 19:42:07 -0800 (PST) From: Waiman Long X-Google-Original-From: Waiman Long Message-ID: <5d755e54-ff86-4cd0-87bf-86290d4f13de@redhat.com> Date: Mon, 3 Nov 2025 22:42:05 -0500 Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCHv4 2/2] sched/deadline: Walk up cpuset hierarchy to decide root domain when hot-unplug To: Pingfan Liu , Juri Lelli Cc: Waiman Long , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Peter Zijlstra , Pierre Gondois , Frederic Weisbecker , Ingo Molnar , Tejun Heo , Johannes Weiner , =?UTF-8?Q?Michal_Koutn=C3=BD?= , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider References: <20251028034357.11055-1-piliu@redhat.com> <20251028034357.11055-2-piliu@redhat.com> <52252077-30cb-4a71-ba2a-1c4ecb36df37@redhat.com> Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 11/3/25 10:34 PM, Pingfan Liu wrote: >> If that is the case, and assuming nobody touched the sleeping task >> affinity (p->cpus_ptr), can't we just use another online cpu from > In fact, IIUC, the change will be always propagated through the cpuset > hier into cpus_ptr by cpuset_update_tasks_cpumask() in cpuset v2. > (Ridong, please correct me if my understanding is wrong) For kthreads, changes to p->cpus_ptr via cpuset is going to be updated with a new set of kthread patch [1] being reviewed right now. [1] https://lore.kernel.org/lkml/20251013203146.10162-1-frederic@kernel.org/ Cheers, Longman