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

H. Peter Anvin
2015-04-30T23:24:10Z

On 04/30/2015 02:39 PM, H. Peter Anvin wrote:
> This is the microbenchmark I used.
>
> For the record, Intel's intention going forward is that 0F 1F will
> always be as fast or faster than any other alternative.
>

I probably should have added that the microbenchmark specifically tests
for an atomic 5-byte NOP (as required by tracepoints etc.) If the
requirement for 5-byte atomic is dropped there might be faster
combinations, e.g. 66 66 66 90 might work better on some platforms, or
using very long 0F 1F sequences.

-hpa