Re: What I suspect : [PATCH] sysdat driver for faster gettimeofday()

John Wright (jwright@cthulhu.engr.sgi.com)
Thu, 9 Dec 1999 21:49:01 -0800

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On Fri, Dec 10, 1999 at 05:13:09AM +0100, Andrea Arcangeli wrote:
> Your gettimeofday has a resolution of 10msec while the stock gettimeofday
> has a resolution of 1/CPU_CYCLES_PER_SEC (order of 2pico-sec) on P5 or
> more recent x86 machines and of 1/8253_LATCH_DOWNCOUNT_FREQUENCY on 486
> and 386 (that is very more accurate than 10msec).
>
> Andrea

Andrea,

How exactly are you figuring the resolution?

I understand that the initial mmap is higher latency but that is
just on the initial call... Every one after that is just a read from
memory.

-- John Wright (jwright@engr.sgi.com)

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