Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755493AbaJUMQF (ORCPT ); Tue, 21 Oct 2014 08:16:05 -0400 Received: from mail-pa0-f50.google.com ([209.85.220.50]:60107 "EHLO mail-pa0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755191AbaJUMQB (ORCPT ); Tue, 21 Oct 2014 08:16:01 -0400 Message-ID: <54464E79.2050601@gmail.com> Date: Tue, 21 Oct 2014 20:15:53 +0800 From: Wanpeng Li User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 MIME-Version: 1.0 To: Juri Lelli , peterz@infradead.org CC: mingo@redhat.com, juri.lelli@gmail.com, raistlin@linux.it, michael@amarulasolutions.com, fchecconi@gmail.com, daniel.wagner@bmw-carit.de, vincent@legout.info, luca.abeni@unitn.it, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/3] sched/deadline: clear dl_entity params when setscheduling to different class References: <1411118561-26323-1-git-send-email-juri.lelli@arm.com> <1411118561-26323-2-git-send-email-juri.lelli@arm.com> <54352ECB.5030507@gmail.com> In-Reply-To: <54352ECB.5030507@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ping, 于 10/8/14, 8:32 PM, Wanpeng Li 写道: > Hi Juri, > > 于 9/19/14, 5:22 PM, Juri Lelli 写道: >> When a task is using SCHED_DEADLINE and the user setschedules it to a >> different >> class its sched_dl_entity static parameters are not cleaned up. This >> causes a >> bug if the user sets it back to SCHED_DEADLINE with the same >> parameters again. >> The problem resides in the check we perform at the very beginning of >> dl_overflow(): >> >> if (new_bw == p->dl.dl_bw) >> return 0; >> >> This condition is met in the case depicted above, so the function >> returns and >> dl_b->total_bw is not updated (the p->dl.dl_bw is not added to it). >> After this, > > As you know there is no static parameter clear before this patch, so > if p->dl.dl_bw will decrease from dl_b->total_bw when the user > setschedules to a different class instead of dl? > > Regards, > Wanpeng Li > >> admission control is broken. >> >> This patch fixes the thing, properly clearing static parameters for a >> task >> that ceases to use SCHED_DEADLINE. >> >> Reported-by: Daniele Alessandrelli >> Reported-by: Daniel Wagner >> Reported-by: Vincent Legout >> Tested-by: Luca Abeni >> Signed-off-by: Juri Lelli >> Cc: Ingo Molnar >> Cc: Peter Zijlstra >> Cc: Juri Lelli >> Cc: Dario Faggioli >> Cc: Michael Trimarchi >> Cc: Fabio Checconi >> Cc: linux-kernel@vger.kernel.org >> --- >> kernel/sched/core.c | 19 +++++++++++++++---- >> kernel/sched/deadline.c | 2 ++ >> kernel/sched/sched.h | 3 +++ >> 3 files changed, 20 insertions(+), 4 deletions(-) >> >> diff --git a/kernel/sched/core.c b/kernel/sched/core.c >> index ec1a286..581a429 100644 >> --- a/kernel/sched/core.c >> +++ b/kernel/sched/core.c >> @@ -1776,6 +1776,20 @@ int wake_up_state(struct task_struct *p, >> unsigned int state) >> } >> /* >> + * This function clears the sched_dl_entity static params. >> + */ >> +void __dl_clear_params(struct task_struct *p) >> +{ >> + struct sched_dl_entity *dl_se = &p->dl; >> + >> + dl_se->dl_runtime = 0; >> + dl_se->dl_deadline = 0; >> + dl_se->dl_period = 0; >> + dl_se->flags = 0; >> + dl_se->dl_bw = 0; >> +} >> + >> +/* >> * Perform scheduler related setup for a newly forked process p. >> * p is forked by current. >> * >> @@ -1799,10 +1813,7 @@ static void __sched_fork(unsigned long >> clone_flags, struct task_struct *p) >> RB_CLEAR_NODE(&p->dl.rb_node); >> hrtimer_init(&p->dl.dl_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); >> - p->dl.dl_runtime = p->dl.runtime = 0; >> - p->dl.dl_deadline = p->dl.deadline = 0; >> - p->dl.dl_period = 0; >> - p->dl.flags = 0; >> + __dl_clear_params(p); >> INIT_LIST_HEAD(&p->rt.run_list); >> diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c >> index 255ce13..4a51b14 100644 >> --- a/kernel/sched/deadline.c >> +++ b/kernel/sched/deadline.c >> @@ -1569,6 +1569,8 @@ static void switched_from_dl(struct rq *rq, >> struct task_struct *p) >> if (hrtimer_active(&p->dl.dl_timer) && !dl_policy(p->policy)) >> hrtimer_try_to_cancel(&p->dl.dl_timer); >> + __dl_clear_params(p); >> + >> #ifdef CONFIG_SMP >> /* >> * Since this might be the only -deadline task on the rq, >> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h >> index 579712f..4890484 100644 >> --- a/kernel/sched/sched.h >> +++ b/kernel/sched/sched.h >> @@ -126,6 +126,9 @@ struct rt_bandwidth { >> u64 rt_runtime; >> struct hrtimer rt_period_timer; >> }; >> + >> +void __dl_clear_params(struct task_struct *p); >> + >> /* >> * To keep the bandwidth of -deadline tasks and groups under control >> * we need some place where: > -- 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/