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    SubjectRe: [Lse-tech] [RFC][Patch 1/5] nanosecond timestamps and diffs
    Shailabh Nagar wrote:
    > Jay Lan wrote:
    >
    >>john stultz wrote:
    >>
    >>
    >>>On Mon, 2005-12-12 at 19:31 +0000, Shailabh Nagar wrote:
    >>>
    >>>
    >>>>Christoph Lameter wrote:
    >>>>
    >>>>
    >>>>>On Wed, 7 Dec 2005, Shailabh Nagar wrote:
    >>>>>
    >>>>>
    >>>>>
    >>>>>
    >>>>>>+void getnstimestamp(struct timespec *ts)
    >>>>>
    >>>>>
    >>>>>
    >>>>>There is already getnstimeofday in the kernel.
    >>>>>
    >>>>
    >>>>Yes, and that function is being used within the getnstimestamp()
    >>>>being proposed.
    >>>>However, John Stultz had advised that getnstimeofday could get
    >>>>affected by calls to
    >>>>settimeofday and had recommended adjusting the getnstimeofday value
    >>>>with wall_to_monotonic.
    >>>>
    >>>>John, could you elaborate ?
    >>>
    >>>
    >>>
    >>>I think you pretty well have it covered.
    >>>getnstimeofday + wall_to_monotonic should be higher-res and more
    >>>reliable (then TSC based sched_clock(), for example) for getting a
    >>>timestamp.
    >>
    >>
    >>How is this proposed function different from
    >>do_posix_clock_monotonic_gettime()?
    >>It calls getnstimeofday(), it also adjusts with wall_to_monotinic.
    >>
    >>It seems to me we just need to EXPORT_SYMBOL_GPL the
    >>do_posix_clock_monotonic_gettime()?
    >>
    >>Thanks,
    >> - jay
    >>
    >
    >
    > Hmmm. Looks like do_posix_clock_monotonic_gettime will suffice for this patch.
    >
    > Wonder why the clock parameter to do_posix_clock_monotonic_get is needed ?

    Because it is called indirectly by the table driven posix clocks and
    timers code where the clock, usually, is needed.

    > Doesn't seem to be used.
    >
    > Any possibility of these set of functions changing their behaviour ?

    Always :), but things are pretty stable now. Might want to add a
    comment that it is being used outside of the posix "box".


    --
    George Anzinger george@mvista.com
    HRT (High-res-timers): http://sourceforge.net/projects/high-res-timers/
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