[PATCH] Add cache info to _dl_x86_cpu_features

[H.J. Lu]

On Sun, May 8, 2016 at 8:57 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
> Support setting processor-specific __x86_shared_non_temporal_threshold
> value in init_cpu_features.
>
> Tested on x86 and x86-64.  Any comments and feebacks?
>
> H.J.
> ---
>         * sysdeps/x86/cacheinfo.c (__x86_shared_non_temporal_threshold):
>         Initialize only if it is zero.
> ---
>  sysdeps/x86/cacheinfo.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/sysdeps/x86/cacheinfo.c b/sysdeps/x86/cacheinfo.c
> index 143b333..788f42d 100644
> --- a/sysdeps/x86/cacheinfo.c
> +++ b/sysdeps/x86/cacheinfo.c
> @@ -669,5 +669,6 @@ init_cacheinfo (void)
>    /* The large memcpy micro benchmark in glibc shows that 6 times of
>       shared cache size is the approximate value above which non-temporal
>       store becomes faster.  */
> -  __x86_shared_non_temporal_threshold = __x86_shared_cache_size * 6;
> +  if (__x86_shared_non_temporal_threshold == 0)
> +    __x86_shared_non_temporal_threshold = __x86_shared_cache_size * 6;
>  }

This doesn't work since init_cpu_features may only update the private copy
in ld.so.  Instead, this patch adds cache info to _dl_x86_cpu_features so
that init_cpu_features sets cache size.

Any comments and feebacks?


-- 
H.J.
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