Messages in this thread | | | Date | Thu, 9 Dec 1999 21:49:01 -0800 | From | John Wright <> | Subject | Re: What I suspect : [PATCH] sysdat driver for faster gettimeofday() |
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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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