Messages in this thread | | | Subject | Re: [PATCH] x86_64, asm: Work around AMD SYSRET SS descriptor attribute issue | From | "H. Peter Anvin" <> | Date | Mon, 27 Apr 2015 13:14:51 -0700 |
| |
I did a microbenchmark in user space... let's see if I can find it.
On April 27, 2015 1:03:29 PM PDT, Borislav Petkov <bp@alien8.de> wrote: >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.
-- Sent from my mobile phone. Please pardon brevity and lack of formatting.
| |