Re: [PATCH 09/40] autonuma: introduce kthread_bind_node()

[Andrea Arcangeli]

On Sat, Jun 30, 2012 at 12:50:14AM -0400, Konrad Rzeszutek Wilk wrote:
> On Thu, Jun 28, 2012 at 02:55:49PM +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@xxxxxxxxxx>
> > ---
> >  include/linux/kthread.h |    1 +
> >  include/linux/sched.h   |    2 +-
> >  kernel/kthread.c        |   23 +++++++++++++++++++++++
> >  3 files changed, 25 insertions(+), 1 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/include/linux/sched.h b/include/linux/sched.h
> > index 4059c0f..699324c 100644
> > --- a/include/linux/sched.h
> > +++ b/include/linux/sched.h
> > @@ -1792,7 +1792,7 @@ extern void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *
> >  #define PF_SWAPWRITE	0x00800000	/* Allowed to write to swap */
> >  #define PF_SPREAD_PAGE	0x01000000	/* Spread page cache over cpuset */
> >  #define PF_SPREAD_SLAB	0x02000000	/* Spread some slab caches over cpuset */
> > -#define PF_THREAD_BOUND	0x04000000	/* Thread bound to specific cpu */
> > +#define PF_THREAD_BOUND	0x04000000	/* Thread bound to specific cpus */
> >  #define PF_MCE_EARLY    0x08000000      /* Early kill for mce process policy */
> >  #define PF_MEMPOLICY	0x10000000	/* Non-default NUMA mempolicy */
> >  #define PF_MUTEX_TESTER	0x20000000	/* Thread belongs to the rt mutex tester */
> > 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_bind - bind a just-created kthread to a cpu.
 * @p: thread created by kthread_create().
 * @cpu: cpu (might not be online, must be possible) for @k to run on.
 *
 * Description: This function is equivalent to set_cpus_allowed(),
 * except that @cpu doesn't need to be online, and the thread must be
 * stopped (i.e., just returned from kthread_create()).
 */
void kthread_bind(struct task_struct *p, unsigned int cpu)
{
	/* 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(cpu));
	p->flags |= PF_THREAD_BOUND;
}
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);

The above should explain why it's not _GPL right now. As far as
AutoNUMA is concerned I can drop the EXPORT_SYMBOL completely and not
allow modules to call this. In fact I could have coded this inside
autonuma too.

I can change it to _GPL, drop the EXPORT_SYMBOL or move it inside the
autonuma code, let me know what you prefer. If I hear nothing I won't
make changes.

Thanks,
Andrea
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