Re: [PATCH] SN2 user-MMIO CPU migration

Jesse Barnes
2006-01-20T02:18:43Z

On Thursday, January 19, 2006 4:06 pm, Brent Casavant wrote:
> #ifndef __ARCH_WANT_UNLOCKED_CTXSW
> static inline int task_running(runqueue_t *rq, task_t *p)
> @@ -936,6 +939,7 @@ static int migrate_task(task_t *p, int d
> * it is sufficient to simply update the task's cpu field.
> */
> if (!p->array && !task_running(rq, p)) {
> + arch_task_migrate(p);
> set_task_cpu(p, dest_cpu);
> return 0;
> }
> @@ -1353,6 +1357,7 @@ static int try_to_wake_up(task_t *p, uns
> out_set_cpu:
> new_cpu = wake_idle(new_cpu, p);
> if (new_cpu != cpu) {
> + arch_task_migrate(p);
> set_task_cpu(p, new_cpu);
> task_rq_unlock(rq, &flags);
> /* might preempt at this point */
> @@ -1876,6 +1881,7 @@ void pull_task(runqueue_t *src_rq, prio_
> {
> dequeue_task(p, src_array);
> dec_nr_running(p, src_rq);
> + arch_task_migrate(p);
> set_task_cpu(p, this_cpu);
> inc_nr_running(p, this_rq);
> enqueue_task(p, this_array);
> @@ -4547,6 +4553,7 @@ static void __migrate_task(struct task_s
> if (!cpu_isset(dest_cpu, p->cpus_allowed))
> goto out;
>
> + arch_task_migrate(p);
> set_task_cpu(p, dest_cpu);
> if (p->array) {
> /*

Maybe you could just turn the above into mmiowb() calls instead? That
would cover altix, origin, and ppc as well I think. On other platforms
it would be a complete no-op.

Jesse