[RFC PATCH] aarch64: improve memset

[Andrew Pinski]

On Sat, Jun 14, 2014 at 12:06 AM, Richard Henderson <rth@twiddle.net> wrote:
> The major idea here is to use IFUNC to check the zva line size once, and use
> that to select different entry points.  This saves 3 branches during startup,
> and allows significantly more flexibility.
>
> Also, I've cribbed several of the unaligned store ideas that Ondrej has done
> with the x86 versions.
>
> I've done some performance testing using cachebench, which suggests that the
> unrolled memset_zva_64 path is 1.5x faster than the current memset at 1024
> bytes and above.  The non-zva path appears to be largely unchanged.
>
> I'd like to use some of Ondrej's benchmarks+data, but I couldn't locate them in
> a quick search of the mailing list.  Pointers?
>
> Comments?

Yes I have a performance regression on ThunderX with this patch and
the newer versions still.  Due to the placement of subs in the inner
most of loop of the non-zero case.  Around a 20% regression.

Thanks,
Andrew Pinski



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