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MathGroup Archive 2005

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Re: Re: Multicore Calculations


Hi, 

this are the informations about my system:

Dual Opteron
2G RAM
SuSE Prof. 9.3
Mathematica 5.2

The threads do not show up independently on this system (it is a
cip-pool). On my local computer, I have only one processor (Athlon64)
with Gentoo (I know, it is not supported) running and there the kernel
uses 4 processes. Can one set from outside (as user or installer) how
many Threads a kernel uses?

Thanks,

Manuel

On Thu, 2005-09-29 at 05:41 -0400, Jeff Bryant wrote:
>    The results you get depend on a couple of factors.  I'll provide a 
> couple comments and perhaps other, more qualified people can respond 
> directly if necessary for additional details.
> 
> What platform (CPU and OS) are you running on? That will determine if
> a) we support multiple processors/cores
> and
> b) if top shows threads independently  of their parent process.
> 
> Also, vector-vector (BLAS level 1) and matrix-vector operations (BLAS 
> level 2) don't parallelize terribly well, so there will be little 
> benefit to multiple processors for those types of operations, anyway.
> 
> -Jeff
> 
> Manuel Schmidt wrote:
> 
> > Hi all,
> > 
> > i'm wondering, how one can convince the MathKernel to do a numerical
> > linear algebra calculation on two processors at the same time in 5.2.
> > 
> > Am I right, that this should be computed on two processors (if
> > available):
> > 
> > vec1 = Table[Random[], {i, 5000000}];
> > vec2 = Table[Random[], {i, 5000000}];
> > 
> > While[True,Dot[vec1, vec2]]
> > 
> > or a big matrix and a vector
> > 
> > matrix.vector;
> > 
> > Anyways, I see in top only one kernel running. There is only one thread.
> > Are there different binaries for the multicore and the singlecore
> > version?
> > 
> > Thanks,
> > 
> > Manuel
> > 
> > 


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