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    SubjectRe: [PATCH 13/39] NLKD/x86-64 - time adjustment
    On Fri, Nov 11, 2005 at 03:12:15AM +0100, Andi Kleen wrote:
    > On Thursday 10 November 2005 15:23, Jan Beulich wrote:
    >
    > >
    > > >Please remove the ifdefs too. 64bit HPET support would be fine, but
    > > >only as a runtime mechanism, not compile time.
    > >
    > > This I added only for the purpose of not affecting existing code in
    > > existing configurations. If the code is generally acceptable, then I'll be
    > > more than happy to convert it.
    >
    > We can't use 64bit HPET everywhere because quite some chipsets only
    > support 32bit HPET. So it has to be a runtime switch depending on the
    > capabilities of the hardware.

    Is there any advantage to using 64-bit HPET? It's read is even slower
    (and thus even more unusable in a vsyscall than a 32-bit HPET read), and
    the missing 32 bits can be quite easily added should we need them for
    computations, which I doubt.

    > > >Can you remove debugger_jiffies please?
    > > >The code has to handle long delays anyways (e.g. if someone uses a target
    > > >probe), so we cannot rely on such hacks anyways.
    > >
    > > As above, I introduced this only to not affect existing code. If the added
    > > latency is no problem, then of course only the overflow safe code path
    > > should be kept, and then debugger_jiffies is completely unnecessary.
    >
    > Hmm - didn't notice anything particularly slow. Or what were you thinking
    > about regarding the latency? And it should only run at each timer interrupt,
    > so it isn't a fast path. So I guess it's best to run it always.

    --
    Vojtech Pavlik
    SuSE Labs, SuSE CR
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