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    SubjectRe: a faster way to gettimeofday?
    Chris Ball wrote:
    >
    > >>>>> "dean" == dean gaudet <dean-list-linux-kernel@arctic.org> writes:
    >
    > dean> ingo started the proper work for this, for example, see:
    > dean> <http://people.redhat.com/mingo/vsyscall-patches/vsyscall-2.3.32-F4>
    > dean> (there's a documentation file near the bottom of the patch)
    > dean> but it doesn't appear to support gettimeofday via rdtsc yet.
    >
    > Interesting patch; when last I looked, vsyscalls were only being
    > implemented on the new 64-bit architectures.
    >
    > Does this patch break binary compatibility? I seem to recall that being
    > Andrea's reason for not running vsyscalls on standard x86 back in August
    > last year.
    >
    In keeping with the subject, the gettimeofday call in this patch does
    NOT get the current timeofday, but the time it was last updated, which
    is usually every 1/HZ. The REAL gettimeofday adds a converted delta of
    the TSC to get the time to NOW with a resolution of 1 micro second.
    (Oh, and by the way, it does not update xtime in the process of doing
    this.)

    As a wonder, just how long is your system taking to do a gettimeofday.
    Mine does it in under one micro second (800 MHZ PIII).

    -g

    > - Chris.
    > --
    > $a="printf.net"; Chris Ball | chris@void.$a | www.$a | finger: chris@$a
    > "In the beginning there was nothing, which exploded."
    >
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    --
    George george@mvista.com
    High-res-timers: http://sourceforge.net/projects/high-res-timers/
    Real time sched: http://sourceforge.net/projects/rtsched/
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