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[72.235.13.41]) by smtp.gmail.com with ESMTPSA id b16-20020aa78710000000b00646e7d2b5a7sm7157908pfo.112.2023.06.06.13.13.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 06 Jun 2023 13:13:31 -0700 (PDT) Sender: Tejun Heo Date: Tue, 6 Jun 2023 10:13:31 -1000 From: Tejun Heo To: Waiman Long Cc: Michal =?iso-8859-1?Q?Koutn=FD?= , Zefan Li , Johannes Weiner , Jonathan Corbet , Shuah Khan , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, Juri Lelli , Valentin Schneider , Frederic Weisbecker , Mrunal Patel , Ryan Phillips , Brent Rowsell , Peter Hunt , Phil Auld Subject: Re: [RFC PATCH 0/5] cgroup/cpuset: A new "isolcpus" paritition Message-ID: References: <759603dd-7538-54ad-e63d-bb827b618ae3@redhat.com> <405b2805-538c-790b-5bf8-e90d3660f116@redhat.com> <18793f4a-fd39-2e71-0b77-856afb01547b@redhat.com> <563fd5e1-650a-e329-8aab-2fa1953a9f49@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <563fd5e1-650a-e329-8aab-2fa1953a9f49@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org Hello, On Tue, Jun 06, 2023 at 04:11:02PM -0400, Waiman Long wrote: ... > The current CPU exclusive behavior is limited to sibling cgroups only. > Because of the hierarchical nature of cpu distribution, the set of exclusive > CPUs have to appear in all its ancestors. When partition is enabled, we do a > sibling exclusivity test at that point to verify that it is exclusive. It > looks like you want to do an exclusivity test even when the partition isn't > active. I can certainly do that when the file is being updated. However, it > will fail the write if the exclusivity test fails just like the v1 > cpuset.cpus.exclusive flag if you are OK with that. Yeah, doesn't look like there's a way around it if we want to make .exclusive a feature which is useful on its own. > > Instead, it can be sth like "if the parent is a > > partition root, cpuset implicitly tries to set all CPUs in its cpus file in > > its cpus.exclusive file" so that user-visible behavior stays unchanged > > depending on past history. > > If parent is a partition root, auto reservation will be done and > cpus.exclusive will be set automatically just like before. So existing > applications using partition will not be affected. Sounds great. Thanks. -- tejun