From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933045AbaJUQYH (ORCPT ); Tue, 21 Oct 2014 12:24:07 -0400 Received: from service87.mimecast.com ([91.220.42.44]:41804 "EHLO service87.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932389AbaJUQYD convert rfc822-to-8bit (ORCPT ); Tue, 21 Oct 2014 12:24:03 -0400 Message-ID: <544688A1.7010403@arm.com> Date: Tue, 21 Oct 2014 17:24:01 +0100 From: Juri Lelli User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: Kirill Tkhai , Peter Zijlstra CC: Kirill Tkhai , "linux-kernel@vger.kernel.org" , Ingo Molnar , Juri Lelli Subject: Re: [PATCH v2 2/3] sched/dl: Cleanup prio_changed_dl() References: <20140930210412.5258.35299.stgit@localhost> <20140930210428.5258.32223.stgit@localhost> <20141002093600.GC2849@worktop.programming.kicks-ass.net> <1412243541.20287.28.camel@tkhai> In-Reply-To: <1412243541.20287.28.camel@tkhai> X-OriginalArrivalTime: 21 Oct 2014 16:24:01.0002 (UTC) FILETIME=[6C2974A0:01CFED4B] X-MC-Unique: 114102117240101901 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Kirill, On 02/10/14 10:52, Kirill Tkhai wrote: > В Чт, 02/10/2014 в 11:36 +0200, Peter Zijlstra пишет: >> On Wed, Oct 01, 2014 at 01:04:35AM +0400, Kirill Tkhai wrote: >>> From: Kirill Tkhai >>> >>> rq->curr task can't be in "dequeued" state in prio_changed_dl(). >>> (The only place we can have that is __schedule()). So, we delete >>> rq->curr check. >> >> the CBS timer can throttle it right? > > Yeah, it's better to check for on_dl_rq(): > > [PATCH]sched/dl: Cleanup prio_changed_dl() > > rq->curr task can't be in "dequeued" state in prio_changed_dl(). > (The only place we can have that is __schedule()). So, we delete > rq->curr check. > > We shouldn't do balancing if deadline task is throttled too. > > Also delete "else" branch which is dead code (switched_to_dl() > is not interested in dequeued tasks and we are not interested > in balancing in this case). > So, I agree that calling switched_to_dl() makes little sense, but don't we have to deal with updates to not running tasks as in rt.c? Something like this maybe? >>From 75ee75a5fd76526baaed3ba8a58f3ff7daa89cd6 Mon Sep 17 00:00:00 2001 From: Juri Lelli Date: Tue, 21 Oct 2014 17:15:15 +0100 Subject: [PATCH] sched/deadline: cleanup prio_changed_dl() --- kernel/sched/deadline.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index 28d6088..1e62e31 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1661,7 +1661,10 @@ static void switched_to_dl(struct rq *rq, struct task_struct *p) static void prio_changed_dl(struct rq *rq, struct task_struct *p, int oldprio) { - if (task_on_rq_queued(p) || rq->curr == p) { + if (!on_dl_rq(&p->dl)) + return; + + if (rq->curr == p) { #ifdef CONFIG_SMP /* * This might be too much, but unfortunately @@ -1688,8 +1691,15 @@ static void prio_changed_dl(struct rq *rq, struct task_struct *p, */ resched_curr(rq); #endif /* CONFIG_SMP */ - } else - switched_to_dl(rq, p); + } else { + /* + * This task is not running, so if its deadline is + * now more imminent than that of the current running + * task then reschedule. + */ + if (dl_time_before(p->dl.deadline, rq->curr->dl.deadline)) + resched_curr(rq); + } } const struct sched_class dl_sched_class = { -- 2.1.0 Thanks, - Juri > Signed-off-by: Kirill Tkhai > > diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c > index 63f8b4a..ccea917 100644 > --- a/kernel/sched/deadline.c > +++ b/kernel/sched/deadline.c > @@ -1638,35 +1638,33 @@ static void switched_to_dl(struct rq *rq, struct task_struct *p) > static void prio_changed_dl(struct rq *rq, struct task_struct *p, > int oldprio) > { > - if (task_on_rq_queued(p) || rq->curr == p) { > + if (!on_dl_rq(&p->dl)) > + return; > #ifdef CONFIG_SMP > - /* > - * This might be too much, but unfortunately > - * we don't have the old deadline value, and > - * we can't argue if the task is increasing > - * or lowering its prio, so... > - */ > - if (!rq->dl.overloaded) > - pull_dl_task(rq); > - > - /* > - * If we now have a earlier deadline task than p, > - * then reschedule, provided p is still on this > - * runqueue. > - */ > - if (dl_time_before(rq->dl.earliest_dl.curr, p->dl.deadline) && > - rq->curr == p) > - resched_curr(rq); > -#else > - /* > - * Again, we don't know if p has a earlier > - * or later deadline, so let's blindly set a > - * (maybe not needed) rescheduling point. > - */ > + /* > + * This might be too much, but unfortunately > + * we don't have the old deadline value, and > + * we can't argue if the task is increasing > + * or lowering its prio, so... > + */ > + if (!rq->dl.overloaded) > + pull_dl_task(rq); > + /* > + * If we now have a earlier deadline task than p, > + * then reschedule, provided p is still on this > + * runqueue. > + */ > + if (dl_time_before(rq->dl.earliest_dl.curr, p->dl.deadline) && > + rq->curr == p) > resched_curr(rq); > +#else > + /* > + * Again, we don't know if p has a earlier > + * or later deadline, so let's blindly set a > + * (maybe not needed) rescheduling point. > + */ > + resched_curr(rq); > #endif /* CONFIG_SMP */ > - } else > - switched_to_dl(rq, p); > } > > const struct sched_class dl_sched_class = { > > >