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Wysocki" , Greg Kroah-Hartman , Danilo Krummrich , Zenghui Yu , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, Kayra Cizmeci , stable@kernel.org Subject: Re: [PATCH v2 1/6] sched/cache: Keep nr_pref_llc_running in the runnable domain Message-ID: <20260922072205.GV4121339@noisy.programming.kicks-ass.net> References: <06af61afedac32e6477f57feb4d658f6c411c3af.1790035273.git.tim.c.chen@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <06af61afedac32e6477f57feb4d658f6c411c3af.1790035273.git.tim.c.chen@linux.intel.com> X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 35917C0003 X-Rspam-User: X-Stat-Signature: 9r8opoaay3nnzz5oeqwdoeinefy8omnh X-HE-Tag: 1790061741-495942 X-HE-Meta: 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 E6Sp1iHB o9oDMrIRcGKia1NAa7GmJytyKbBOzammkrsI/Hnz4rcV2tFrUbi77A30l1x0BoH3Ukr+wZqedBh+Lrnrxh8RElPmxtJ8ON1rQjHi2xJt1QQ6D9yAFvLE3LnK8763nxDtvRXRO1rULeLZxRSsdyUa8jTmNzTyewJIOorZwVYhdEYdQ7XqEVVVGYzRdCBLw1JWqdtj6Wo6kc+paSFjc7jzjIIl+fTdTr5BUP5y/pDnc68WuEDpD3AOvm1+36wRyk4HZds/74CqRa+no3rscyA9TcyaYzXYnvLH8pcy0nzEpmOqwy/esOx5JHG6hCxndw3DeDGIM0uel2H8ZqpX2eLhjgveJbPp8dgcoqUXezn4IpeWNv3s= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Sep 21, 2026 at 05:37:22PM -0700, Tim Chen wrote: > @@ -6395,15 +6429,27 @@ static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq); > > static void set_delayed(struct sched_entity *se) > { > - se->sched_delayed = 1; > - > /* > * Delayed se of cfs_rq have no tasks queued on them. > * Do not adjust h_nr_runnable since __dequeue_task() > * will account it for blocked tasks. > + * > + * This check can be removed because when flat pick > + * patches get merged as only task can get delayed, > + * same for clear_delayed(). > */ > - if (!entity_is_task(se)) > + if (!entity_is_task(se)) { > + se->sched_delayed = 1; > return; > + } This is dead code. In Linus' tree, where this will be applied, this can never happen. A possible backport of this fix however will need to take care. > + > + /* > + * Drop a task leaving the runnable set. > + * Needs to be called before sched_delayed is set. > + * clear_delayed() mirrors this after clearing the flag. > + */ > + pref_llc_running_dec(rq_of(cfs_rq_of(se)), task_of(se)); > + se->sched_delayed = 1; > > for_each_sched_entity(se) { > struct cfs_rq *cfs_rq = cfs_rq_of(se);