On Wed, Jun 18, 2014 at 11:37:35AM +0800, Lai Jiangshan wrote:
> > @@ -97,7 +98,10 @@ static inline void percpu_ref_kill(struct percpu_ref
> > *ref)
> > static inline bool __pcpu_ref_alive(struct percpu_ref *ref,
> > unsigned __percpu **pcpu_countp)
> > {
> > - unsigned long pcpu_ptr = ACCESS_ONCE(ref->pcpu_count_ptr);
> > + unsigned long pcpu_ptr;
> > +
> > + /* paired with smp_store_release() in percpu_ref_reinit() */
> > + pcpu_ptr = smp_load_acquire(&ref->pcpu_count_ptr);
>
>
> Does "smp_load_acquire()" hurts the performance of percpu_ref_get/put()
> in non-x86 system?
It's equivalent to data dependency barrier. The only arch which needs
something more than barrier() is alpha. It isn't an issue.
Thanks.
--
tejun
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