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Thu, 07 May 2026 08:03:44 -0700 (PDT) Received: from jlelli-thinkpadt14gen4.remote.csb ([176.206.7.99]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-45055960fd6sm22020103f8f.31.2026.05.07.08.03.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 07 May 2026 08:03:43 -0700 (PDT) Date: Thu, 7 May 2026 17:03:41 +0200 From: Juri Lelli To: Peter Zijlstra Cc: Tejun Heo , Yuri Andriaccio , Ingo Molnar , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , linux-kernel@vger.kernel.org, Luca Abeni , Yuri Andriaccio , hannes@cmpxchg.org, mkoutny@suse.com, cgroups@vger.kernel.org Subject: Re: [RFC PATCH v5 20/29] sched/deadline: Allow deeper hierarchies of RT cgroups Message-ID: References: <20260430213835.62217-1-yurand2000@gmail.com> <20260430213835.62217-21-yurand2000@gmail.com> <20260505151523.GF3102624@noisy.programming.kicks-ass.net> <20260507105331.GQ1026330@noisy.programming.kicks-ass.net> Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260507105331.GQ1026330@noisy.programming.kicks-ass.net> On 07/05/26 12:53, Peter Zijlstra wrote: > On Tue, May 05, 2026 at 09:56:58AM -1000, Tejun Heo wrote: ... > > - However, the cpu controller is a threaded controller which means that it > > can have threaded sub-hierarchy where the no-internal-process rule doesn't > > apply. This was created explicitly for cpu controller. The proposed change > > blocks it effectively forcing cpu controller into regular domain > > controller behavior subject to no-internal-process rule. Note these are > > enforced at controller granularity and this means that users who use the > > threaded mode will be forced to pick between the two. > > Right... this then means we need two controls, one to do hierarchical > bandwidth distribution, and one to assign bandwidth to the internal > group -- which is then subject to its own bandwidth distribution > constraint. > > This might be a little confusing, but there is no way around that > AFAICT. Just to check if I'm following, you are thinking something like below? groupA/ cpu.rt.max = "50 50 100" <- 0.5 from root cpu.rt.internal = "20 20 100" <- 0.2 from groupA for threads at this level + threadA < + threadB < +- group1/ cpu.rt.max = "30 30 100" <- 0.3 from groupA + threadC And we still keep it flat, so 2 dl-entities (per CPU), one handles threads at groupA level and the other threads inside group1? Thanks, Juri