From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161118AbaDJNqT (ORCPT ); Thu, 10 Apr 2014 09:46:19 -0400 Received: from forward2h.mail.yandex.net ([84.201.187.147]:50268 "EHLO forward2h.mail.yandex.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030713AbaDJNqR (ORCPT ); Thu, 10 Apr 2014 09:46:17 -0400 X-Greylist: delayed 454 seconds by postgrey-1.27 at vger.kernel.org; Thu, 10 Apr 2014 09:46:17 EDT From: Kirill Tkhai To: Michael wang , Sasha Levin , Peter Zijlstra , "ktkhai@parallels.com" Cc: Ingo Molnar , LKML In-Reply-To: <53464164.5030701@linux.vnet.ibm.com> References: <5304F32A.4040907@oracle.com> <5305856F.3000109@linux.vnet.ibm.com> <53078241.3060201@oracle.com> <53080122.609@linux.vnet.ibm.com> <530ABB44.5000601@oracle.com> <530AD653.3000808@linux.vnet.ibm.com> <20140224071028.GW9987@twins.programming.kicks-ass.net> <530B1B80.4000307@linux.vnet.ibm.com> <20140224121218.GR15586@twins.programming.kicks-ass.net> <534610A4.5000302@oracle.com> <53464164.5030701@linux.vnet.ibm.com> Subject: Re: sched: hang in migrate_swap MIME-Version: 1.0 Message-Id: <336561397137116@web27h.yandex.ru> X-Mailer: Yamail [ http://yandex.ru ] 5.0 Date: Thu, 10 Apr 2014 17:38:36 +0400 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=koi8-r Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 10.04.2014, 11:00, "Michael wang" : > On 04/10/2014 11:31 AM, Sasha Levin wrote: > [snip] > >> šI'd like to re-open this issue. It seems that something broke and I'm >> šnow seeing the same issues that have gone away 2 months with this patch >> šagain. > > A new mechanism has been designed to move the priority checking inside > idle_balance(), including Kirill who is the designer ;-) Not sure, it's connected with my patch. But looks like, we forgot exactly stop class. Maybe this will help? [PATCH] sched: Checking for stop task appearance when balancing happens Just do it, like we do for other higher priority classes... Signed-off-by: Kirill Tkhai --- kernel/sched/deadline.c | 11 ++++++++++- kernel/sched/fair.c | 3 ++- kernel/sched/rt.c | 7 ++++--- 3 files changed, 16 insertions(+), 5 deletions(-) diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index 27ef409..b080957 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1021,8 +1021,17 @@ struct task_struct *pick_next_task_dl(struct rq *rq, struct task_struct *prev) dl_rq = &rq->dl; - if (need_pull_dl_task(rq, prev)) + if (need_pull_dl_task(rq, prev)) { pull_dl_task(rq); + /* + * pull_rt_task() can drop (and re-acquire) rq->lock; this + * means a stop task can slip in, in which case we need to + * re-start task selection. + */ + if (rq->stop && rq->stop->on_rq) + 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. diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 7e9bd0b..c50275b 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6727,7 +6727,8 @@ static int idle_balance(struct rq *this_rq) out: /* Is there a task of a high priority class? */ if (this_rq->nr_running != this_rq->cfs.h_nr_running && - (this_rq->dl.dl_nr_running || + ((this_rq->stop && this_rq->stop->on_rq) || + this_rq->dl.dl_nr_running || (this_rq->rt.rt_nr_running && !rt_rq_throttled(&this_rq->rt)))) pulled_task = -1; diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index d8cdf16..bd2267a 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -1362,10 +1362,11 @@ pick_next_task_rt(struct rq *rq, struct task_struct *prev) pull_rt_task(rq); /* * pull_rt_task() can drop (and re-acquire) rq->lock; this - * means a dl task can slip in, in which case we need to - * re-start task selection. + * means a dl or stop task can slip in, in which case we need + * to re-start task selection. */ - if (unlikely(rq->dl.dl_nr_running)) + if (unlikely((rq->stop && rq->stop->on_rq) || + rq->dl.dl_nr_running)) return RETRY_TASK; }