[concurrency-interest] micro benchmark hell

Kasper Nielsen kav at it.edu
Tue Sep 19 04:48:34 EDT 2006


  > I'm running it on a 2 way Opterton w/ Linux kernel v2.6.17.11 w/ Sun
> JVM 1.5.0_08.  The problem I'm having is if I execute it often enough
> eventually "Sum" will be greater than "Total time elapsed". Which as
> far as I'm concerned is supposed to be impossible.
> 
> Now it could be that because it's 4:30 AM and my brain is fried I'm
> overlooking the obvious but I doubt it.  Any feedback would be greatly
> appreciated.
> 
> Regards,
> 
> Dane Foster

Hi Dane,

Lets say:

Thread1-Thread8 uses 1 s each on Processor 1
Thread9-Thread16 uses 1 s each on Processor 2

That's 16 seconds in total. But only 8 seconds in wall clock time 
(excluding time spent on starting/joining threads)

- Kasper




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