On Fri, Nov 04, 2016 at 05:18:29PM +0100, Andrew Jones wrote:
> On Wed, Oct 26, 2016 at 03:47:08PM +0800, Peter Xu wrote:
> > This will be useful to be put inside loops.
> >
> > Suggested-by: Andrew Jones <drjones@xxxxxxxxxx>
> > Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
> > ---
> > lib/x86/asm/barrier.h | 11 +++++++++++
> > 1 file changed, 11 insertions(+)
> >
> > diff --git a/lib/x86/asm/barrier.h b/lib/x86/asm/barrier.h
> > index 7c108bd..193fb4c 100644
> > --- a/lib/x86/asm/barrier.h
> > +++ b/lib/x86/asm/barrier.h
> > @@ -13,4 +13,15 @@
> > #define smp_rmb() barrier()
> > #define smp_wmb() barrier()
> >
> > +/* REP NOP (PAUSE) is a good thing to insert into busy-wait loops. */
> > +static inline void rep_nop(void)
> > +{
> > + asm volatile("rep; nop" ::: "memory");
> > +}
> > +
> > +static inline void cpu_relax(void)
> > +{
> > + rep_nop();
> > +}
> > +
> > #endif
> > --
> > 2.7.4
>
> Reviewed-by: Andrew Jones <drjones@xxxxxxxxxx>
>
> But this should be the first patch of the series, because your current
> first patch already introduces one busy-wait loop where it could be used.
I missed that patch. Will fix and reorder. Thanks,
-- peterx
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