[erlang-questions] Chameneos.rednux micro benchmark

[Kevin Scaldeferri]

On Oct 10, 2008, at 12:54 PM, Greg Burri wrote:

> Hi,
> I'm very surprise to see the differences between these two same  
> benchmarks on shootout.alioth.debian.org :
> 1) Quad core : http://shootout.alioth.debian.org/u64q/benchmark.php?test=chameneosredux&lang=hipe
> 2) Mono core : http://shootout.alioth.debian.org/u64/benchmark.php?test=chameneosredux&lang=hipe
>
> Here are the CPU times :
> 1) 2095.18 s
> 2) 37.03 s
>
> I try on my machine[1] with a) "-smp enable" and b) "-smp disable" :
> a) 47.863 s
> b) 18.285
>
> Maybe It's not strange to see a such difference because of inter-cpu  
> message passing. But the difference on shootout.alioth.debian.org is  
> too large
> What should we do ?

Are you using HiPE?  There's some chance that could explain some of  
the relative difference.

I don't think message passing is the issue.  I suspect it's lack of  
process affinity.  The chameneos processes are likely getting bounced  
around between schedulers constantly.

In the short term, I'm not sure what can be done other than requesting  
the benchmark be run with '-S 1', which really kinda defeats the  
purpose.  It would be nice to have a different solution, as I agree  
that this situation is pretty embarrassing.  This task is such a  
natural for the actor-model and Erlang; it's a shame the performance  
ends up being so poor.

-k
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