Re: [PATCH] x86_64, asm: Work around AMD SYSRET SS descriptor attribute issue

Borislav Petkov
2015-04-27T20:03:53Z

On Mon, Apr 27, 2015 at 12:59:11PM -0700, H. Peter Anvin wrote:
> It really comes down to this: it seems older cores from both Intel
> and AMD perform better with 66 66 66 90, whereas the 0F 1F series is
> better on newer cores.
>
> When I measured it, the differences were sometimes dramatic.

How did you measure that? I should probably do the same on some newer
AMD machines... We're using k8_nops on all AMD, even though the
optimization manuals cite different NOPs on newer AMD families.

Thanks.

--
Regards/Gruss,
Boris.

ECO tip #101: Trim your mails when you reply.
--