linux-kernel - Re: [PATCH 5/6] sched/dl: reschedule if successfully pull earlier deadline task

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Message-ID: <20141030131259.GA474@kernel>
Date:	Thu, 30 Oct 2014 21:12:59 +0800
From:	Wanpeng Li <wanpeng.li@...ux.intel.com>
To:	Juri Lelli <juri.lelli@....com>
Cc:	Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"juri.lelli@...il.com" <juri.lelli@...il.com>
Subject: Re: [PATCH 5/6] sched/dl: reschedule if successfully pull earlier
 deadline task

Hi Juri,
On Thu, Oct 30, 2014 at 10:21:00AM +0000, Juri Lelli wrote:
>Hi,
>
>On 27/10/14 01:41, Wanpeng Li wrote:
>> Reschedule if successfully pull earlier deadline task.
>> 
>> Signed-off-by: Wanpeng Li <wanpeng.li@...ux.intel.com>
>> ---
>>  kernel/sched/deadline.c | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>> 
>> diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
>> index 97141e2..21de865 100644
>> --- a/kernel/sched/deadline.c
>> +++ b/kernel/sched/deadline.c
>> @@ -1583,8 +1583,8 @@ static void switched_from_dl(struct rq *rq, struct task_struct *p)
>>  	 * this is the right place to try to pull some other one
>>  	 * from an overloaded cpu, if any.
>>  	 */
>> -	if (!rq->dl.dl_nr_running)
>> -		pull_dl_task(rq);
>> +	if (!rq->dl.dl_nr_running && pull_dl_task(rq))
>> +			resched_curr(rq);
>
>Right, we have to reschedule. But, how about we fully align to -rt?
>
>Peter, is the task_on_rq_queued() check for cases in which p is not
>enqueued but its class changes after a setscheduler/rt_mutex_setprio?
>
>Thanks,
>
>- Juri
>
>>>From 404749782e493cb6019193f347163b640ebd552d Mon Sep 17 00:00:00 2001
>From: Juri Lelli <juri.lelli@....com>
>Date: Thu, 30 Oct 2014 10:15:40 +0000
>Subject: [PATCH] sched/deadline: reschedule from switched_from_dl() after a
> successful pull
>
>In switched_from_dl() we have to issue a resched if we
>successfully pulled some task from other cpus.
>This patch also aligns the behaviour with -rt.
>

Good idea.

>Signed-off-by: Juri Lelli <juri.lelli@....com>

I will send out version two of this patchset with the update of 2/6 and
5/6 with *your Suggested-by*. Thanks for your great proposal. ;-)

Regards,
Wanpeng Li

>Suggested-by: Wanpeng Li <wanpeng.li@...ux.intel.com>
>---
> kernel/sched/deadline.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
>diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
>index db6ad38..e8943fc 100644
>--- a/kernel/sched/deadline.c
>+++ b/kernel/sched/deadline.c
>@@ -1623,8 +1623,11 @@ static void switched_from_dl(struct rq *rq, struct task_struct *p)
> 	 * this is the right place to try to pull some other one
> 	 * from an overloaded cpu, if any.
> 	 */
>-	if (!rq->dl.dl_nr_running)
>-		pull_dl_task(rq);
>+	if (!task_on_rq_queued(p) || rq->dl.dl_nr_running)
>+		return;
>+
>+	if (pull_dl_task(rq))
>+		resched_curr(rq);
> #endif
> }
> 
>-- 
>2.1.2
--
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