I started working on a patch, but I'm not sure if it is the right thing to just encode a longer static array of primes. Any suggestions on how to proceed? Should I generate the array of primes on-the-fly (once per MPI instance) up to the max possible amount? Jeff ---------- Forwarded message ---------- From: Jeff Hammond <[email protected]> Date: Thu, Dec 19, 2013 at 10:55 AM Subject: Re: [mpich-discuss] MPI_Dims_create() fails for nproc >1000000 To: [email protected] Can you provide a short test that reproduces the issue you are seeing? I will add a Trac ticket for it. Thanks, Jeff On Thu, Dec 19, 2013 at 9:49 AM, Andreas Schäfer <[email protected]> wrote:

Hi,

I noticed that MPICH's MPI_Dims_create() fails with a floating point exception, if the number of processes is larger than 10^6. Apparently the reason is that the prime factors are hard coded into the code and are limited to 1000 (or sqrt(10^6)). Open MPI's implementation has no such limitation.

Best -Andreas

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