Re: [PATCH RT] fix rt-task scheduling issue

[Gregory Haskins <ghaskins@novell.com>]

Hi Guys,
  Nice find!  Comment inline..

(adding linux-rt-users)

 for reference to

 http://lkml.org/lkml/2007/10/8/252

On Mon, 2007-10-08 at 22:46 -0400, Steven Rostedt wrote:
> Index: linux-2.6.23-rc9-rt2/kernel/sched.c
> ===================================================================
> --- linux-2.6.23-rc9-rt2.orig/kernel/sched.c
> +++ linux-2.6.23-rc9-rt2/kernel/sched.c
> @@ -2207,7 +2207,7 @@ static inline void finish_task_switch(st
>  	 * If we pushed an RT task off the runqueue,
>  	 * then kick other CPUs, they might run it:
>  	 */
> -	if (unlikely(rt_task(current) && prev->se.on_rq && rt_task(prev))) {
> +	if (unlikely(rt_task(current) && rq->rt_nr_running > 1)) {
>  		schedstat_inc(rq, rto_schedule);
>  		smp_send_reschedule_allbutself_cpumask(current->cpus_allowed);

the current->cpus_allowed I think probably should have been
"prev->cpus_allowed" in the original code?  However, in light of the new
findings with this bug Mike found, this should probably be sent to
allbutself() without the mask since you don't know what could have been
queued behind you.

Unless I am missing something?

Regards,
-Greg


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