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, Sebastian Andrzej Siewior Subject: Re: [PATCH v4 3/5] sched/fair: Switch to task based throttle model Message-ID: <20250905075338.GK42@bytedance> References: <20250829081120.806-1-ziqianlu@bytedance.com> <20250829081120.806-4-ziqianlu@bytedance.com> <20250903145124.GM4067720@noisy.programming.kicks-ass.net> <14be66aa-e088-4267-ac10-d04d600b1294@amd.com> <20250904081611.GE42@bytedance> <20250904120401.GJ42@bytedance> Precedence: bulk X-Mailing-List: linux-kernel@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: <20250904120401.GJ42@bytedance> On Thu, Sep 04, 2025 at 08:04:01PM +0800, Aaron Lu wrote: ... ... > Per my understanding, we keep PELT clock running because we want the > throttled cfs_rq's load to continue get update when it still has tasks > running in kernel mode and have that up2date load could let it have a > hopefully more accurate weight through update_cfs_group(). So it looks > to me, if PELT clock should not be stopped, then we should not abort in > propagate_entity_cfs_rq() and update_cfs_group(). I missed these two > aborts in these two functions, but now you and Peter have pointed this > out, I suppose there is no doubt we should not abort in > update_cfs_group() and propagate_entity_cfs_rq()? If we should not mess > with shares distribution, then the up2date load is not useful and why > not simply freeze PELT clock on throttle :) With more thinking, when PELT clock is running, root level cfs_rq's load can be updated and that is useful for things like load balance. update_cfs_group() is a different story and as Ben said, there is cons and pros whether to abort there for throttled cfs_rq so there's no obvious thing to do for it.