From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753109Ab1FQCdb (ORCPT ); Thu, 16 Jun 2011 22:33:31 -0400 Received: from mailout-de.gmx.net ([213.165.64.23]:47974 "HELO mailout-de.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1752013Ab1FQCda (ORCPT ); Thu, 16 Jun 2011 22:33:30 -0400 X-Authenticated: #14349625 X-Provags-ID: V01U2FsdGVkX1+suP51giassAvTcOTMXbM4Mz9FCMWXXHPEexplYY xMKDCgzjmzgQ8K Subject: Re: [RFC][PATCH 4/7] sched, rt: Fix rq->rt.pushable_tasks bug in push_rt_task() From: Mike Galbraith To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Andrew Morton , Peter Zijlstra , Yong Zhang , Hillf Danton , Mike Galbraith In-Reply-To: <20110617015919.136959032@goodmis.org> References: <20110617015516.301117218@goodmis.org> <20110617015919.136959032@goodmis.org> Content-Type: text/plain; charset="UTF-8" Date: Fri, 17 Jun 2011 04:33:25 +0200 Message-ID: <1308278005.15063.12.camel@marge.simson.net> Mime-Version: 1.0 X-Mailer: Evolution 2.32.1 Content-Transfer-Encoding: 7bit X-Y-GMX-Trusted: 0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2011-06-16 at 21:55 -0400, Steven Rostedt wrote: > plain text document attachment > (0004-sched-rt-Fix-rq-rt.pushable_tasks-bug-in-push_rt_tas.patch) > From: Hillf Danton > > Do not call dequeue_pushable_task() when failing to push an eligible > task, as it remains pushable, merely not at this particular moment. > > Cc: Yong Zhang > Cc: Peter Zijlstra > Signed-off-by: Hillf Danton > Signed-off-by: Mike Galbraith Mixing addresses doesn't work. Less bouncy SOB. Signed-off-by: Mike Galbraith > Link: http://lkml.kernel.org/r/1306895385.4791.26.camel@marge.simson.net > Signed-off-by: Steven Rostedt > --- > kernel/sched_rt.c | 15 ++++++++------- > 1 files changed, 8 insertions(+), 7 deletions(-) > > diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c > index a6f1f64..7737d41 100644 > --- a/kernel/sched_rt.c > +++ b/kernel/sched_rt.c > @@ -1378,6 +1378,7 @@ static int push_rt_task(struct rq *rq) > { > struct task_struct *next_task; > struct rq *lowest_rq; > + int ret = 0; > > if (!rq->rt.overloaded) > return 0; > @@ -1410,7 +1411,7 @@ retry: > if (!lowest_rq) { > struct task_struct *task; > /* > - * find lock_lowest_rq releases rq->lock > + * find_lock_lowest_rq releases rq->lock > * so it is possible that next_task has migrated. > * > * We need to make sure that the task is still on the same > @@ -1420,12 +1421,11 @@ retry: > task = pick_next_pushable_task(rq); > if (task_cpu(next_task) == rq->cpu && task == next_task) { > /* > - * If we get here, the task hasn't moved at all, but > - * it has failed to push. We will not try again, > - * since the other cpus will pull from us when they > - * are ready. > + * The task hasn't migrated, and is still the next > + * eligible task, but we failed to find a run-queue > + * to push it to. Do not retry in this case, since > + * other cpus will pull from us when ready. > */ > - dequeue_pushable_task(rq, next_task); > goto out; > } > > @@ -1444,6 +1444,7 @@ retry: > deactivate_task(rq, next_task, 0); > set_task_cpu(next_task, lowest_rq->cpu); > activate_task(lowest_rq, next_task, 0); > + ret = 1; > > resched_task(lowest_rq->curr); > > @@ -1452,7 +1453,7 @@ retry: > out: > put_task_struct(next_task); > > - return 1; > + return ret; > } > > static void push_rt_tasks(struct rq *rq)