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    SubjectRe: [RFC][PATCH] Dynamic Tick: Allow 32-bit machines to sleep for more than 2.15 seconds
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    On Tue, 2009-04-21 at 18:20 -0500, Jon Hunter wrote:
    > john stultz wrote:
    > > The concern is many clocksources wrap after a handful of seconds. The
    > > acpi_pm is the best example (its only 24 bits wide).
    > >
    > > I brought this issue up earlier, and provided some example code that
    > > could be used to limit the idle time appropriately for the current
    > > clocksource here:
    > >
    > > http://lkml.indiana.edu/hypermail/linux/kernel/0901.3/02693.html
    > >
    > > Jon: Did you see that mail, or is there a reason you didn't adapt this
    > > code into your patch?
    >
    > Hi John, yes I did read this email and thanks for bringing this up.
    >
    > As I looked at this more I noticed that for 64-bit machines that the
    > max_delta_ns would be a 64-bit integer already and so this change would
    > only have an impact for 32-bit machines. I understand that there are
    > more 32-bit machines that 64-bit. However, I was trying to understand
    > how the wrapping of clocksources, such as the one you mention above, is
    > handled today for 64-bit machines that could theoretically sleep for
    > longer periods.

    One other minor comment nit, if we're really meaning that max_delta_ns
    is a 64bit value, should we not just be using s64 and be explicit
    instead of converting longs to long longs?

    thanks
    -john




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