lkml.org 
[lkml]   [2011]   [Aug]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [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


    \
     
     \ /
      Last update: 2011-08-24 23:13    [W:7.306 / U:0.004 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site