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

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Message-ID: <5452110C.40108@arm.com>
Date:	Thu, 30 Oct 2014 10:21:00 +0000
From:	Juri Lelli <juri.lelli@....com>
To:	Wanpeng Li <wanpeng.li@...ux.intel.com>,
	Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>
CC:	"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,

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.

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