[Beowulf] MPI_Isend/Irecv failure for IB and large message sizes

[Greg Lindahl]

On Mon, Nov 16, 2009 at 10:49:23AM -0700, Michael H. Frese wrote:

> Could it be that your MPI library was compiled using a small memory  
> model?  The 180 million doubles sounds suspiciously close to a 2 GB  
> addressing limit.
>
> This issue came up on the list recently under the topic "Fortran Array 
> size question."

If you need a memory model other than the default small, you'll get a
particular error message at link time; here's an example courtesy of
the Intel software forums, but I bet that every compiler for Linux
includes an example in their manual:

/tmp/ifort3X7vjE.o: In function `sph':
sph.f:41: relocation truncated to fit: R_X86_64_PC32 against `.bss'
sph.f:94: relocation truncated to fit: R_X86_64_PC32 against `.bss'
sph.f:94: relocation truncated to fit: R_X86_64_PC32 against `.bss'
sph.f:94: relocation truncated to fit: R_X86_64_PC32 against `.bss'

And it's only when your BSS is too big, not variables on the stack or
allocated/malloced. I really doubt this is the problem either now or
before.

-- greg