Re: [PATCH v2 3/3][RT] sched: Have migrate_disable ignore bounded threads

[Steven Rostedt <rostedt@goodmis.org>]

On Tue, 2011-09-27 at 08:40 -0400, Steven Rostedt wrote:
> plain text document attachment
> (peterz-migrate-disable-thread-bound.patch)
> From: Peter Zijlstra <a.p.zijlstra@chello.nl>


Thomas,

Hold off on this patch until we get the kworker/u straighten out. I'm
retesting with the following change:

@@ -1383,7 +1384,7 @@ static struct worker *create_worker(struct global_cwq *gcwq, bool bind)
        if (bind && !on_unbound_cpu)
                kthread_bind(worker->task, gcwq->cpu);
        else {
-               worker->task->flags |= PF_THREAD_BOUND;
+//             worker->task->flags |= PF_THREAD_BOUND;
                if (on_unbound_cpu)
                        worker->flags |= WORKER_UNBOUND;
        }

So far, so good.

-- Steve

> 
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
> 
> Index: linux-rt.git/kernel/sched.c
> ===================================================================
> --- linux-rt.git.orig/kernel/sched.c
> +++ linux-rt.git/kernel/sched.c
> @@ -4247,7 +4247,7 @@ void migrate_disable(void)
>  {
>  	struct task_struct *p = current;
>  
> -	if (in_atomic()) {
> +	if (in_atomic() || p->flags & PF_THREAD_BOUND) {
>  #ifdef CONFIG_SCHED_DEBUG
>  		p->migrate_disable_atomic++;
>  #endif
> @@ -4278,7 +4278,7 @@ void migrate_enable(void)
>  	unsigned long flags;
>  	struct rq *rq;
>  
> -	if (in_atomic()) {
> +	if (in_atomic() || p->flags & PF_THREAD_BOUND) {
>  #ifdef CONFIG_SCHED_DEBUG
>  		p->migrate_disable_atomic--;
>  #endif
> @@ -4299,26 +4299,21 @@ void migrate_enable(void)
>  
>  	if (unlikely(migrate_disabled_updated(p))) {
>  		/*
> -		 * See comment in update_migrate_disable() about locking.
> +		 * Undo whatever update_migrate_disable() did, also see there
> +		 * about locking.
>  		 */
>  		rq = this_rq();
>  		raw_spin_lock_irqsave(&rq->lock, flags);
> -		mask = tsk_cpus_allowed(p);
> +
>  		/*
>  		 * Clearing migrate_disable causes tsk_cpus_allowed to
>  		 * show the tasks original cpu affinity.
>  		 */
>  		p->migrate_disable = 0;
> -
> -		WARN_ON(!cpumask_test_cpu(smp_processor_id(), mask));
> -
> -		if (unlikely(!cpumask_equal(&p->cpus_allowed, mask))) {
> -			/* Get the mask now that migration is enabled */
> -			mask = tsk_cpus_allowed(p);
> -			if (p->sched_class->set_cpus_allowed)
> -				p->sched_class->set_cpus_allowed(p, mask);
> -			p->rt.nr_cpus_allowed = cpumask_weight(mask);
> -		}
> +		mask = tsk_cpus_allowed(p);
> +		if (p->sched_class->set_cpus_allowed)
> +			p->sched_class->set_cpus_allowed(p, mask);
> +		p->rt.nr_cpus_allowed = cpumask_weight(mask);
>  		raw_spin_unlock_irqrestore(&rq->lock, flags);
>  	} else
>  		p->migrate_disable = 0;