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Re^9: Limit on number of cores

Alex Granovsky

Hi Vyacheslav,

I searched through mpich-smp.dll and did not find any string
resembling "PROCESSOR_COUNT". Most likely, you will not be able
to use more than 32 cores with nt-mpich-smp. I'd suggest you to
switch to MS MPI for this purpose. It is free and can be found here:

Alex Granovsky

On Thu Feb 16 '12 11:17am, Vyacheslav wrote
>thanks very much!  I set variable value MPI_GLOBMEMSIZE=536870912  forever :-)
>Now FF works up to 32 cores. I found the following text:

>"By default, mpich limits the number of processes for the ch_shmem device to 32, unless it determines at configure time that the machine has more processors.
>You can override this limit by setting the environment variable PROCESSOR_COUNT to the maximum number of processes that you will want to run, and then reconfigure and remake mpich."

>Does it concern the given restriction? If yes, what to do? I am far from such things.

>On Wed Feb 15 '12 7:47pm, Alex Granovsky wrote

>>this is not the Firefly command line option!.
>>This is rather the environment variable which you need to set
>>either in the batch file calling Firefly or permanently here:


Computer->Properties->Advanced system settings->Advanced->Environment variables

>>The latter will take effect on all sessions launched after you have
>>made some changes so you need to start fresh command prompt or other
>>shell program you may use.

>>Alex Granovsky

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