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    SubjectRe: rdtsc to mili secs?
    On Sat, Nov 18, 2000 at 09:12:31PM +0100, Pavel Machek wrote:

    > > Anyway, this should be solvable by checking for clock change in the
    > > timer interrupt. This way we should be able to detect when the clock
    > > went weird with a 10 ms accuracy. And compensate for that. It should be
    > > possible to keep a 'reasonable' clock running even through the clock
    > > changes, where reasonable means constantly growing and as close to real
    > > time as 10 ms difference max.
    > >
    > > Yes, this is not perfect, but still keep every program quite happy and
    > > running.
    > No. Udelay has just gone wrong and your old ISA xxx card just crashed
    > whole system. Oops.

    Yes. But can you do any better than that? Anyway, I wouldn't expect to
    be able to put my old ISA cards into a recent notebook which fiddles
    with the CPU speed (or STPCLK ratio).

    > BTW I mailed patch to do exactly that kind of autodetection to the
    > list some time ago. (I just can't find it now :-( -- search archives
    > for 'TSC is slower than it should be'.

    If I recall correctly, that patch didn't create a 'reasonable clock' -
    it wasn't growing all the time and could skip back sometimes.

    Vojtech Pavlik
    SuSE Labs
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