Re: test time-warps [was: Re: 2.6.14-rt13]

From: Lee Revell
Date: Mon Nov 21 2005 - 20:31:24 EST

On Mon, 2005-11-21 at 15:41 -0800, john stultz wrote:
> I believe this is the same dual-core TSC drift that has been seen w/
> x86-64. I have just added some similar logic to the TSC clocksource
> that mimics what x86-64 does so an alternative clocksource will be
> selected automatically.
> I should be sending out another release later tonight with these
> updates.

It is really unfortunate that the TSC cannot be used for timekeeping on
these machines. I wrote a simple benchmark that shows rdtsc on
Fernando's box to be insanely fast - 10000 iterations in 68
microseconds. This was an order of magnitude faster than any other
machine we tested. Why would they bother making it so fast if it's
useless for timekeeping?


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