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.
drew
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