[Beowulf] mpich program segfaults

Douglas Eadline, Cluster World Magazine deadline at linux-mag.com
Thu Mar 4 17:34:29 EST 2004


What type of machine is this?

Doug


On Wed, 3 Mar 2004, Glen Kaukola wrote:

> Suvendra Nath Dutta wrote:
> 
> > Glen,
> >     Does your program seg fault when compiled with debugging off or on?
> 
> 
> Either way.
> 
> > Sometimes compilers will initialize arrays when compiling for 
> > debugging, but not waste time doing that when compiled without debugging.
> 
> 
> The arguments being passed to the subroutine are two arrays of real 
> numbers and a few integers.  Nothing being passed to the subroutine has 
> been dynamically allocated.  The compiler, IBM's XLF compiler, 
> initializes the array to 0.  At least I'm pretty sure it does, since I 
> can print things before the subroutine call.
> 
> > Also if you compile with optimization which line follows which one 
> > isn't always clear.
> 
> 
> I don't have any optimizations turned on.
> 
> > You want to make sure you aren't over-running memory.
> 
> 
> The machine has 2 gigs of memory, which should be plenty.  The same 
> program runs on an x86 machine with 1 gig of memory just fine (I'm 
> trying to get the program working on an Apple G5 by the way).
> 
> > Also you want to be sure its nothing to do with MPICH. Try calling the 
> > subroutine from a serial program if possible.
> 
> 
> I've tried telling mpirun to only use one cpu and I get the same 
> results.  I've also tried running the program all by itself and it still 
> crashes.  Like I said though, it runs just fine under the a debugger.
> 
> 
> Glen
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