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

[Konrad Rzeszutek Wilk <konrad@darnok.org>]

On Fri, May 25, 2012 at 07:02:12PM +0200, Andrea Arcangeli wrote:
> This function makes it easy to bind the per-node knuma_migrated
> threads to their respective NUMA nodes. Those threads take memory from
> the other nodes (in round robin with a incoming queue for each remote
> node) and they move that memory to their local node.
> 
> Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
> ---
>  include/linux/kthread.h |    1 +
>  kernel/kthread.c        |   23 +++++++++++++++++++++++
>  2 files changed, 24 insertions(+), 0 deletions(-)
> 
> diff --git a/include/linux/kthread.h b/include/linux/kthread.h
> index 0714b24..e733f97 100644
> --- a/include/linux/kthread.h
> +++ b/include/linux/kthread.h
> @@ -33,6 +33,7 @@ struct task_struct *kthread_create_on_node(int (*threadfn)(void *data),
>  })
>  
>  void kthread_bind(struct task_struct *k, unsigned int cpu);
> +void kthread_bind_node(struct task_struct *p, int nid);
>  int kthread_stop(struct task_struct *k);
>  int kthread_should_stop(void);
>  bool kthread_freezable_should_stop(bool *was_frozen);
> diff --git a/kernel/kthread.c b/kernel/kthread.c
> index 3d3de63..48b36f9 100644
> --- a/kernel/kthread.c
> +++ b/kernel/kthread.c
> @@ -234,6 +234,29 @@ void kthread_bind(struct task_struct *p, unsigned int cpu)
>  EXPORT_SYMBOL(kthread_bind);
>  
>  /**
> + * 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;
> +}
> +EXPORT_SYMBOL(kthread_bind_node);

_GPL?

> +
> +/**
>   * kthread_stop - stop a thread created by kthread_create().
>   * @k: thread created by kthread_create().
>   *
> 
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