Re: [uml-devel] SYSCALL, ptrace and syscall restart breakages (Re: [RFC] weird crap with vdso on uml/i386)

H. Peter Anvin
2011-08-23T21:07:11Z

On 08/23/2011 01:56 PM, Borislav Petkov wrote:
>
> But no, I don't think the difference has disappeared - to the contrary,
> AFAICT, the intention is for SYSCALL to be the fastest way to do
> syscalls on x86 due to diminished number of segment checks etc. INT80
> is legacy, slower, etc. I believe Andy measured a similar situation on
> Sandy Bridge with SYSCALL having latencies in the tens of nsecs range
> and INT80 being much slower. Ingo also measured a similar situation
> where the latency gap between the two on Intel is even bigger.
>

Sandy Bridge doesn't have SYSCALL32 at all. It has SYSENTER and SYSCALL64.

-hpa