Messages in this thread | | | Date | Wed, 24 Aug 2011 14:10:04 -0700 | From | "H. Peter Anvin" <> | Subject | Re: [uml-devel] SYSCALL, ptrace and syscall restart breakages (Re: [RFC] weird crap with vdso on uml/i386) |
| |
On 08/23/2011 02:10 PM, Borislav Petkov wrote: > On Tue, Aug 23, 2011 at 05:06:03PM -0400, H. Peter Anvin wrote: >> 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. > > Yeah, I was talking about SYSCALL in general. >
By the way, Borislav;
any way you could nudge your hardware people into
a) supporting SYSENTER in compatibility mode, and b) giving us a way to turn SYSCALL *off* in compat mode?
... for future chips?
-hpa
| |