Messages in this thread | | | Date | Tue, 13 Dec 2005 14:13:15 -0800 | From | George Anzinger <> | Subject | Re: [Lse-tech] [RFC][Patch 1/5] nanosecond timestamps and diffs |
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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/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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