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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: <20220526225141.GA1214445@lothringen> <9e44bb00-955a-dbc6-a863-be649e0c701f@redhat.com> <20220527083018.n43nc73vuuzm5ixo@localhost.localdomain> <20220530004049.GA1251147@lothringen> <20220530105650.GA1257179@lothringen> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org On 30/05/22 15:16, Peter Zijlstra wrote: > On Mon, May 30, 2022 at 12:56:50PM +0200, Frederic Weisbecker wrote: > > > > This is ABI, you can't walk back on it. I would suggest starting with an > > > 'all feature' isolation. Only if there's real demand for something more > > > fine-grained add that on top. Simple first etc. > > > > That's actually my worry. If we start with an all in one ABI, how do we later > > mix that up with more finegrained features? Like what will be the behaviour of: > > > > cpuset.isolation.rcu_nocb = 0 > > cpuset.isolation.all = 1 > > Well clearly that doesn't make sense. I was more thinking along the > lines of cgroup.subtree_control, where instead all features are enabled > by default. > > But only if there's a real usecase, otherwise there's no point in > providing such knobs. All features on/off knob + house-keeping sub-partition/mask seem to be what isolation users I could reach so far (OCP mostly) would indeed like to have in the future.