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Sat, 17 Oct 2026 23:58:00 -0700 (PDT) Date: Sun, 18 Oct 2026 09:57:57 +0300 From: Kayra Cizmeci To: Vincent Guittot Cc: mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, kprateek.nayak@amd.com, linux-kernel@vger.kernel.org, lukasz.luba@arm.com, rafael@kernel.org, linux-pm@vger.kernel.org, tj@kernel.org, void@manifault.com, arighi@nvidia.com, changwoo@igalia.com, sched-ext@lists.linux.dev, qyousef@layalina.io, christian.loehle@arm.com, pierre.gondois@arm.com, sshegde@linux.ibm.com Subject: Re: [PATCH 07/18] sched/fair: Add push task mechanism for fair Message-ID: References: <20261002154415.2270586-1-vincent.guittot@linaro.org> <20261002154415.2270586-8-vincent.guittot@linaro.org> 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=utf-8 Content-Disposition: inline In-Reply-To: <20261002154415.2270586-8-vincent.guittot@linaro.org> On Fri, Oct 02, 2026 at 05:44:04PM +0200, Vincent Guittot wrote: > +static void __fair_add_pushable_task(struct rq *rq, struct task_struct *p) > +{ > + plist_del(&p->pushable_tasks, &rq->cfs.pushable_tasks); > + plist_node_init(&p->pushable_tasks, p->prio); > + plist_add(&p->pushable_tasks, &rq->cfs.pushable_tasks); > +} > + > +static void fair_add_pushable_prev(struct rq *rq, struct task_struct *prev, struct task_struct *next) > +{ > + if (sched_push_task_enabled() && fair_check_pushable_task(rq, prev, next)) > + __fair_add_pushable_task(rq, prev); > +} > + > /* > * select_task_rq_fair: Select a target runqueue for the task. > * There are 2 ways to select the target runqueue: > @@ -10272,6 +10426,12 @@ static void put_prev_task_fair(struct rq *rq, struct task_struct *prev, struct t > cfs_rq->curr = NULL; > if (se->on_rq) > __enqueue_entity(cfs_rq, se); > + > + /* > + * The previous task might be eligible for being pushed on another cpu > + * if it is still active. > + */ > + fair_add_pushable_prev(rq, prev, next); > } > > /* Re-reviewed this :-) On our rq, we have a fair task TA that holds M mutex. we have a RT task TB blocked on M. we enter __schedule() and from there pick_next_task(). it chooses TB as next, but it adds TA to the pushable task list. then we enter the proxy exec path. donor is set to TB. but when we enter find_proxy_task(), next is changed to TA. so right now, TA is on the push list even if its still curr. (With the whole series applied.) Am I missing something? Should curr not be pushed? Thanks, Kayra