[PATCH] sched: try to rewrite tg_has_rt_tasks()

[PATCH] sched: try to rewrite tg_has_rt_tasks()

[Hillf Danton]

It is reshuffled not based upon scanning the list of existing threads
but upon the relevant info carried by the input task group. Compared
with the original, it is simpler, and nothing important is missed.

Signed-off-by: Hillf Danton <dhillf@gmail.com>
---

--- a/kernel/sched.c	2011-03-30 03:09:48.000000000 +0800
+++ b/kernel/sched.c	2011-04-23 21:48:14.000000000 +0800
@@ -8756,13 +8756,11 @@ static unsigned long to_ratio(u64 period
 /* Must be called with tasklist_lock held */
 static inline int tg_has_rt_tasks(struct task_group *tg)
 {
-	struct task_struct *g, *p;
-
-	do_each_thread(g, p) {
-		if (rt_task(p) && rt_rq_of_se(&p->rt)->tg == tg)
+	int cpu;
+	for_each_online_cpu(cpu) {
+		if (tg->rt_rq[cpu]->rt_nr_running != 0)
 			return 1;
-	} while_each_thread(g, p);
-
+	}
 	return 0;
 }

Re: [PATCH] sched: try to rewrite tg_has_rt_tasks()

[Yong Zhang]

On Sat, Apr 23, 2011 at 09:39:40PM +0800, Hillf Danton wrote:
> It is reshuffled not based upon scanning the list of existing threads
> but upon the relevant info carried by the input task group. Compared
> with the original, it is simpler, and nothing important is missed.

Oh, no.

There may be sleep task which is attach this group.

Thanks,
Yong

> 
> Signed-off-by: Hillf Danton <dhillf@gmail.com>
> ---
> 
> --- a/kernel/sched.c	2011-03-30 03:09:48.000000000 +0800
> +++ b/kernel/sched.c	2011-04-23 21:48:14.000000000 +0800
> @@ -8756,13 +8756,11 @@ static unsigned long to_ratio(u64 period
>  /* Must be called with tasklist_lock held */
>  static inline int tg_has_rt_tasks(struct task_group *tg)
>  {
> -	struct task_struct *g, *p;
> -
> -	do_each_thread(g, p) {
> -		if (rt_task(p) && rt_rq_of_se(&p->rt)->tg == tg)
> +	int cpu;
> +	for_each_online_cpu(cpu) {
> +		if (tg->rt_rq[cpu]->rt_nr_running != 0)
>  			return 1;
> -	} while_each_thread(g, p);
> -
> +	}
>  	return 0;
>  }
> --
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Re: [PATCH] sched: try to rewrite tg_has_rt_tasks()

[Hillf Danton]

On Sat, Apr 23, 2011 at 10:11 PM, Yong Zhang <yong.zhang0@gmail.com> wrote:
> On Sat, Apr 23, 2011 at 09:39:40PM +0800, Hillf Danton wrote:
>> It is reshuffled not based upon scanning the list of existing threads
>> but upon the relevant info carried by the input task group. Compared
>> with the original, it is simpler, and nothing important is missed.
>
> Oh, no.
>
> There may be sleep task which is attach this group.
>

Would you please say a few more words about the "sleep task"?

Thanks
           Hillf

Re: [PATCH] sched: try to rewrite tg_has_rt_tasks()

[Yong Zhang]

On Sat, Apr 23, 2011 at 10:19:19PM +0800, Hillf Danton wrote:
> On Sat, Apr 23, 2011 at 10:11 PM, Yong Zhang <yong.zhang0@gmail.com> wrote:
> > On Sat, Apr 23, 2011 at 09:39:40PM +0800, Hillf Danton wrote:
> >> It is reshuffled not based upon scanning the list of existing threads
> >> but upon the relevant info carried by the input task group. Compared
> >> with the original, it is simpler, and nothing important is missed.
> >
> > Oh, no.
> >
> > There may be sleep task which is attach this group.
> >
> 
> Would you please say a few more words about the "sleep task"?

Only RUNNING task is counted to rt_nr_running, SLEEP task
is not on the run queue.

Thanks,
Yong