Messages in this thread | | | Date | Mon, 14 Nov 2005 16:38:23 -0800 | From | George Anzinger <> | Subject | Re: [PATCH 13/39] NLKD/x86-64 - time adjustment |
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Vojtech Pavlik wrote: > On Sat, Nov 12, 2005 at 06:21:11PM +0100, Andi Kleen wrote: > >>On Saturday 12 November 2005 10:22, Vojtech Pavlik wrote: >> >> >>>Is there any advantage to using 64-bit HPET? >> >>Yes - it can tolerate long delays between ticks, e.g. caused by noidletick / >>debuggers / target probes / smm etc. At least the first case will be fairly >>important soon. > > > A 32-bit 14 MHz HPET counter will overflow in approximately 5 minutes. I > don't think going 64-bit makes sense for noidletick, but for debuggers, > etc, it could make a good sense indeed. > > >>>It's read is even slower >> >>Why? The read should be on cache line granuality and there shouldn't >>be any difference in theory. > > > I'll try to measure this. Indeed, in theory there shouldn't be a > significant difference. > Doesn't this depend on the atomic nature of the 64-bit read? If it is really two 32-bit reads one would need to do extra work to make sure the two parts belong together.
-- 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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