[Beowulf] MPI & ScaLAPACK: error in MPI_Comm_size: Invalid communicator

Anthony Skjellum tony at mpi-softtech.com
Wed Oct 20 06:39:19 PDT 2004

Just my two cents...

Size is an out parameter, so it should be an address.
Depending on the MPI, MPI_Comm is also secretly mapped to a pointer, but 
it could also be
an index into an array structure (or hash) inside the MPI.  So, it is 
hard to infer anything from
the value of comm...

It would be interesting to do printf("%x %x",(int)MPI_COMM_WORLD,&size)

before calling the Scalapack to get an idea of these quantities...


Mark Hahn wrote:

>>MPI_Comm_size(82): MPI_Comm_size(comm=0x5b, size=0x80d807c) failed
>I have no insight into any of this, except that these parameters 
>are obviously reversed.  0x5b is a sensible size, and 0x80d807c
>is not.  but 0x80d807c is a sensible pointer...
>if this isn't a source-level transposition, perhaps it has to do 
>with mixed calling conventions?
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