Re: [PATCH 08/35] autonuma: introduce kthread_bind_node()

Peter Zijlstra
2012-05-29T12:49:46Z

On Fri, 2012-05-25 at 19:02 +0200, Andrea Arcangeli wrote:
> /**
> + * kthread_bind_node - bind a just-created kthread to the CPUs of a node.
> + * @p: thread created by kthread_create().
> + * @nid: node (might not be online, must be possible) for @k to run on.
> + *
> + * Description: This function is equivalent to set_cpus_allowed(),
> + * except that @nid doesn't need to be online, and the thread must be
> + * stopped (i.e., just returned from kthread_create()).
> + */
> +void kthread_bind_node(struct task_struct *p, int nid)
> +{
> + /* Must have done schedule() in kthread() before we set_task_cpu */
> + if (!wait_task_inactive(p, TASK_UNINTERRUPTIBLE)) {
> + WARN_ON(1);
> + return;
> + }
> +
> + /* It's safe because the task is inactive. */
> + do_set_cpus_allowed(p, cpumask_of_node(nid));
> + p->flags |= PF_THREAD_BOUND;

No, I've said before, this is wrong. You should only ever use
PF_THREAD_BOUND when its strictly per-cpu. Moving the your numa threads
to a different node is silly but not fatal in any way.

> +}
> +EXPORT_SYMBOL(kthread_bind_node);