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([2601:188:c102:b180:1f8b:71d0:77b1:1f6e]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-88d9aa363e3sm337038506d6.57.2026.01.04.14.26.18 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 04 Jan 2026 14:26:19 -0800 (PST) From: Waiman Long X-Google-Original-From: Waiman Long Message-ID: <5ed163d8-c229-4aed-bc8a-ae9cba9b78ec@redhat.com> Date: Sun, 4 Jan 2026 17:26:18 -0500 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [cgroup/for-6.20 PATCH v2 4/4] cgroup/cpuset: Don't invalidate sibling partitions on cpuset.cpus conflict To: Chen Ridong , Tejun Heo , Johannes Weiner , =?UTF-8?Q?Michal_Koutn=C3=BD?= , Jonathan Corbet , Shuah Khan Cc: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-doc@vger.kernel.org, Sun Shaojie References: <20260101191558.434446-1-longman@redhat.com> <20260101191558.434446-5-longman@redhat.com> Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 1/4/26 2:53 AM, Chen Ridong wrote: > > On 2026/1/2 3:15, Waiman Long wrote: >> Currently, when setting a cpuset's cpuset.cpus to a value that conflicts >> with the cpuset.cpus/cpuset.cpus.exclusive of a sibling partition, >> the sibling's partition state becomes invalid. This is overly harsh and >> is probably not necessary. >> >> The cpuset.cpus.exclusive control file, if set, will override the >> cpuset.cpus of the same cpuset when creating a cpuset partition. >> So cpuset.cpus has less priority than cpuset.cpus.exclusive in setting up >> a partition. However, it cannot override a conflicting cpuset.cpus file >> in a sibling cpuset and the partition creation process will fail. This >> is inconsistent. That will also make using cpuset.cpus.exclusive less >> valuable as a tool to set up cpuset partitions as the users have to >> check if such a cpuset.cpus conflict exists or not. >> >> Fix these problems by strictly adhering to the setting of the >> following control files in descending order of priority when setting >> up a partition. >> >> 1. cpuset.cpus.exclusive.effective of a valid partition >> 2. cpuset.cpus.exclusive >> 3. cpuset.cpus >> > Hi, Longman, > > This description is a bit confusing to me. cpuset.cpus.exclusive and cpuset.cpus are user-settable > control files, while cpuset.cpus.exclusive.effective is a read-only file that reflects the result of > applying cpuset.cpus.exclusive and cpuset.cpus after conflict resolution. > > A partition can be established as long as cpuset.cpus.exclusive.effective is not empty. I believe > cpuset.cpus.exclusive.effective represents the final effective CPU mask used for the partition, so > it shouldn't be compared in priority with cpuset.cpus.exclusive or cpuset.cpus. Rather, the latter > two are inputs that determine the former. Yes, that priority list can be somewhat confusing. I will take out this paragraph. The next 2 paragraphs in the commit log should be good enough. Thanks, Longman