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McKenney" , Paul Gortmaker , Johannes Weiner , Marcelo Tosatti , Phil Auld , Zefan Li , Daniel Bristot de Oliveira , Nicolas Saenz Julienne , rcu@vger.kernel.org Subject: Re: [RFC PATCH 4/4] cpuset: Support RCU-NOCB toggle on v2 root partitions Message-ID: References: <20220525221055.1152307-1-frederic@kernel.org> <20220525221055.1152307-5-frederic@kernel.org> <20220526225141.GA1214445@lothringen> <9e44bb00-955a-dbc6-a863-be649e0c701f@redhat.com> <20220527083018.n43nc73vuuzm5ixo@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220527083018.n43nc73vuuzm5ixo@localhost.localdomain> X-Spam-Status: No, score=-2.0 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RDNS_NONE,SPF_HELO_NONE,T_SCC_BODY_TEXT_LINE autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 27, 2022 at 10:30:18AM +0200, Juri Lelli wrote: > Hi, > > On 26/05/22 14:37, Tejun Heo wrote: > > On Thu, May 26, 2022 at 08:28:43PM -0400, Waiman Long wrote: > > > I am thinking along the line that it will not be hierarchical. However, > > > cpuset can be useful if we want to have multiple isolated partitions > > > underneath the top cpuset with different isolation attributes, but no more > > > sub-isolated partition with sub-attributes underneath them. IOW, we can only > > > set them at the first level under top_cpuset. Will that be useful? > > > > At that point, I'd just prefer to have it under /proc or /sys. > > FWIW, I was under the impression that this would nicely fit along the > side of other feaures towards implenting dynamic isolation of CPUs (say > https://lore.kernel.org/lkml/20220510153413.400020-1-longman@redhat.com/ > for example). Wouldn't be awkward to have to poke different places to > achieve isolation at runtime? This, that's what I was thinking. My main objection to the whole thing is that it's an RCU_NOCB specific interface. *That* I think is daft. I was thinking a partition would be able to designate a house-keeping sub-partition/mask, but who cares about all the various different housekeeping parties.