lkml.org 
[lkml]   [2002]   [Dec]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: Intel P6 vs P7 system call performance
    Pavel Machek wrote:
    > Hi!
    >
    >
    >>>>don't many of the multi-CPU problems with tsc go away because you've got a
    >>>>per-cpu physical page for the vsyscall?
    >>>>
    >>>>i.e. per-cpu tsc epoch and scaling can be set on that page.
    >>>
    >>>Problem is that cpu's can randomly drift +/- 100 clocks or so... Not
    >>>nice at all.
    >>>
    >>
    >>­­?100 clocks is what... ?50 ns these days? You can't get that kind of
    >>accuracy for anything outside the CPU core anyway...
    >
    > 50ns is bad enough when it makes your time go backwards.
    >

    Backwards?? Clock spreading should make the rate change, but it should
    never decrement.

    -hpa


    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2005-03-22 13:31    [W:0.025 / U:30.672 seconds]
    ©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site