Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754773AbbEZNcJ (ORCPT ); Tue, 26 May 2015 09:32:09 -0400 Received: from relay.parallels.com ([195.214.232.42]:52914 "EHLO relay.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751427AbbEZNcD (ORCPT ); Tue, 26 May 2015 09:32:03 -0400 Message-ID: <1432641008.6866.59.camel@odin.com> Subject: [PATCH 2/2] sched: Update runtime of prev task before doing pick_next_task() From: Kirill Tkhai To: CC: Peter Zijlstra , Konstantin Khlebnikov , Mohammed Naser , "Ingo Molnar" , Kirill Tkhai Date: Tue, 26 May 2015 14:50:08 +0300 In-Reply-To: <20150526114344.14783.90095.stgit@pro> References: <20150526114344.14783.90095.stgit@pro> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.9-1+b1 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Originating-IP: [10.30.16.109] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2660 Lines: 81 pick_next_task() puts prev rq's task. This may lead to runtime expiration and to dequeueing of all scheduling class's tasks because of throttling. And the current logic is that put_prev_task() must be called in the pick method of next task's class. This was fixed for RT and DL classes, while fair class have this problem. So, instead of doing partial solutions, let's update prev task's runtime for all classes in __schedule() and fix the problem completelly. Also, let's freeze the clock during pick_next_task() to be sure new expirations of runtime won't happen. Reported-by: Konstantin Khlebnikov Reported-by: Mohammed Naser Signed-off-by: Kirill Tkhai --- kernel/sched/core.c | 3 +++ kernel/sched/deadline.c | 7 ------- kernel/sched/rt.c | 7 ------- 3 files changed, 3 insertions(+), 14 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 4eec607..0872280 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2806,7 +2806,10 @@ static void __sched __schedule(void) if (task_on_rq_queued(prev)) update_rq_clock(rq); + prev->sched_class->update_curr(rq); + /* freeze clock to avoid new run time expirations in pick_next_task() */ + rq_clock_skip_update(rq, true); next = pick_next_task(rq, prev); clear_tsk_need_resched(prev); clear_preempt_need_resched(); diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index 7a08d59..570eadd 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1102,13 +1102,6 @@ struct task_struct *pick_next_task_dl(struct rq *rq, struct task_struct *prev) return RETRY_TASK; } - /* - * When prev is DL, we may throttle it in put_prev_task(). - * So, we update time before we check for dl_nr_running. - */ - if (prev->sched_class == &dl_sched_class) - update_curr_dl(rq); - if (unlikely(!dl_rq->dl_nr_running)) return NULL; diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index 7d7093c5..3437e7e 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -1480,13 +1480,6 @@ pick_next_task_rt(struct rq *rq, struct task_struct *prev) return RETRY_TASK; } - /* - * We may dequeue prev's rt_rq in put_prev_task(). - * So, we update time before rt_nr_running check. - */ - if (prev->sched_class == &rt_sched_class) - update_curr_rt(rq); - if (!rt_rq->rt_queued) return NULL; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/