On Mon, Jun 03, 2013 at 08:33:13AM +0200, Paolo Bonzini wrote:
> Il 02/06/2013 17:32, Gleb Natapov ha scritto:
> > On Thu, May 30, 2013 at 07:43:07PM +0200, Paolo Bonzini wrote:
> >> This patch includes two fixes for SB:
> >>
> >> * the 3rd fixed counter ("ref cpu cycles") can sometimes report
> >> less than the number of iterations
> >>
> > Is it documented? It is strange for "architectural" counter to behave
> > differently on different architectures.
>
> It just counts the CPU cycles. If the CPU can optimize the loop better,
> it will take less CPU cycles to execute it.
>
We should try and change the loop so that it will not be so easily optimized.
Making the test succeed if only 10% percent of cycles were spend on a loop
may result in the test missing the case when counter counts something
different.
--
Gleb.
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