linux-kernel - Re: [PATCH v13] sched/deadline: support dl task migration during cpu hotplug

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Date:	Fri, 27 Mar 2015 07:00:45 +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>,
	Wanpeng Li <wanpeng.li@...ux.intel.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v13] sched/deadline: support dl task migration during cpu
 hotplug

Hi Juri,
On Thu, Mar 26, 2015 at 11:14:37AM +0000, Juri Lelli wrote:
>
>I think we could have better naming and the BUG_ON part could be
>simplified. I'd propose something like this (sorry, it is based
>on one of your previous versions.. I'm a bit struggling keeping
>up with the pace ;)).

Cool, thanks for your help, I will send a newer version later. ;)

Regards,
Wanpeng Li 

>
>Thanks!
>
>---
> kernel/sched/deadline.c | 20 +++++++++-----------
> 1 file changed, 9 insertions(+), 11 deletions(-)
>
>diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
>index 1820d1b..2b260a9 100644
>--- a/kernel/sched/deadline.c
>+++ b/kernel/sched/deadline.c
>@@ -518,7 +518,7 @@ static int start_dl_timer(struct sched_dl_entity *dl_se, bool boosted)
> 
> static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq);
> 
>-static void dl_task_migration(struct rq *rq, struct task_struct *p)
>+static void dl_task_offline_migration(struct rq *rq, struct task_struct *p)
> {
> 	struct rq *later_rq = NULL;
> 	bool fallback = false;
>@@ -535,14 +535,12 @@ static void dl_task_migration(struct rq *rq, struct task_struct *p)
> 		fallback = true;
> 		cpu = cpumask_any_and(cpu_active_mask, tsk_cpus_allowed(p));
> 		if (cpu >= nr_cpu_ids) {
>-			if (dl_bandwidth_enabled()) {
>-				/*
>-				 * Fail to find any suitable cpu.
>-				 * The task will never come back!
>-				 */
>-				WARN_ON(1);
>-				return;
>-			}
>+			/*
>+			 * Fail to find any suitable cpu.
>+			 * The task will never come back!
>+			 */
>+			BUG_ON(dl_bandwidth_enabled());
>+
> 			/*
> 			 * If admission control is disabled we
> 			 * try a little harder to let the task
>@@ -609,11 +607,11 @@ static enum hrtimer_restart dl_task_timer(struct hrtimer *timer)
> 	update_rq_clock(rq);
> 
> 	/*
>-	 * So if we find that the rq the task was on is no longer
>+	 * If we find that the rq the task was on is no longer
> 	 * available, we need to select a new rq.
> 	 */
> 	if (unlikely(!rq->online)) {
>-		dl_task_migration(rq, p);
>+		dl_task_offline_migration(rq, p);
> 		goto unlock;
> 	}
> 
>-- 
>2.3.0
--
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