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Re: Performance--Dual Core

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  • Subject: [mg70123] Re: [mg70089] Performance--Dual Core
  • From: "Christoph Lhotka" <lhotka at>
  • Date: Wed, 4 Oct 2006 05:59:39 -0400 (EDT)

Hi ! 

When using Windows you have to tell the OS the following:

> ----------------------------------------
> Variable Name : OMP_NUM_THREADS
> Variable Value: % NUMBER_OF_PROCESSORS% (e.g. 2)
> ----------------------------------------

(first create a new variable OMP_NUM_THREADS as a System Variable in the
Device Manager, then set the NUMBER_OF_PROCESSORS to 2 (or 3, ...). The values
of OMP_NUM_THREADS should be equal to the value of NUMBER_OF_PROCESSORS...

After doing so, you will see, that Mathematica will use both cores for its


On Tue, 3 Oct 2006 06:16:29 -0400 (EDT)
 oparadis at wrote:
> I have just bought a new system (AMD 64 X2 Dual Core 4200+) thinking it
> would improve computations with mathematica 5.2. I am mainly running
> symbolic computation problems (Solve,Reduce,FullSimplify stuff) involving a
> system of nonlinear equations with domain restrictions over parameters...
> I am puzzled by the fact mathematica seems to be using the CPU resources
> from a single core at the time even though the problem it tries to solve is
> very complicated (takes 1 day approx.). While computing, windows' task
> manager shows "MathKernel" using 50% of CPU and "System Idle Process" using
> the remaining 50%.
> I have 2 questions. First, what's going on ? Is Mathematica really unable
> to use both cores at the same time ? Second, how can one deal with this ?
> Is there a way to force mathematica to somehow split the task between both
> cores ?
> I know some of the previous posts have dealt with similar issues but they
> don't quite seem to answer my specific problem.
> Link to the forum page for this post:
> Posted through [[postId=14120]]

-- Mag. Christoph Lhotka --
University of Vienna / Department of Astronomy
Tuerkenschanzstrasse 17, A-1180 Vienna, Austria
fon. +43 (1) 4277 51841
mail. lhotka at

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