From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Fri, 20 Jul 2018 14:53:29 +0200 From: Juri Lelli To: Peter Zijlstra Cc: Daniel Bristot de Oliveira , linux-kernel@vger.kernel.org, Clark Williams , Luca Abeni , Tommaso Cucinotta , Steven Rostedt , Ingo Molnar , stable@vger.kernel.org Subject: Re: [PATCH V3] sched/deadline: Update rq_clock of later_rq when pushing a task Message-ID: <20180720125329.GD3642@localhost.localdomain> References: <20180720124615.GM2476@hirez.programming.kicks-ass.net> <20180720124821.GB2512@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180720124821.GB2512@hirez.programming.kicks-ass.net> Sender: linux-kernel-owner@vger.kernel.org List-ID: On 20/07/18 14:48, Peter Zijlstra wrote: > On Fri, Jul 20, 2018 at 02:46:15PM +0200, Peter Zijlstra wrote: > > On Fri, Jul 20, 2018 at 11:16:30AM +0200, Daniel Bristot de Oliveira wrote: > > > diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c > > > index fbfc3f1d368a..8b50eea4b607 100644 > > > --- a/kernel/sched/deadline.c > > > +++ b/kernel/sched/deadline.c > > > @@ -2090,8 +2090,14 @@ static int push_dl_task(struct rq *rq) > > > sub_rq_bw(&next_task->dl, &rq->dl); > > > set_task_cpu(next_task, later_rq->cpu); > > > add_rq_bw(&next_task->dl, &later_rq->dl); > > > + > > > + /* > > > + * Update the later_rq clock here, because the clock is used > > > + * by the cpufreq_update_util() inside __add_running_bw(). > > > + */ > > > + update_rq_clock(later_rq); > > > add_running_bw(&next_task->dl, &later_rq->dl); > > > - activate_task(later_rq, next_task, 0); > > > + activate_task(later_rq, next_task, ENQUEUE_NOCLOCK); > > > ret = 1; > > > > > > resched_curr(later_rq); > > > > Why isn't push_rt_task() affected by the very same issue? > > Aah, I see, its the add_running_bw() think; for which RT doesn't have a > counter-part. Right, but doesn't enqueue_top_rt_rq end-up being called by activate_ task on lowest_rq? Mmm.