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Subject: Re: [OMPI users] Memory question and possible bug in 64bit addressing under Leopard!
From: Michael (mklus_at_[hidden])
Date: 2008-04-25 16:24:45


On Apr 25, 2008, at 4:10 PM, Brian Barrett wrote:

> On Apr 25, 2008, at 2:06 PM, Gregory John Orris wrote:
>
>> produces a core dump on a machine with 12Gb of RAM.
>>
>> and the error message
>>
>> mpiexec noticed that job rank 0 with PID 75545 on node mymachine.com
>> exited on signal 4 (Illegal instruction).
>>
>> However, substituting in
>>
>> float *X = new float[n];
>> for
>> float X[n];
>>
>> Succeeds!
>
>
> You're running off the end of the stack, because of the large amount
> of data you're trying to put there. OS X by default has a tiny stack
> size, so codes that run on Linux (which defaults to a much larger
> stack size) sometimes show this problem. Your best bets are either to
> increase the max stack size or (more portably) just allocate
> everything on the heap with malloc/new.

Where are Fortran 90 arrays allocated, stack or heap? I can't see us
using malloc in our Fortran 90 codes, I need to understand this before
I start configuring a new clusters, I was planning for it to run OS X
instead of Linux. At the moment I don't have an OS X system with
enough RAM to test this.

Michael