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From: Benoit Semelin (benoit.semelin_at_[hidden])
Date: 2006-03-06 08:11:23

>>Second topic:
>>I am using 3 processors
>>I am calling a series of MPI_SCATTER which work when I send
>>messages of
>>5 ko to the other processors, fails at the second scatter if I sent
>>messages of ~10 ko, and fails at the first scatter for bigger
>>The message is:
>What is "ko" -- did you mean "kb"?

I meant kilobytes (not kilobits). Sorry for that. It comes from
"kilo-octet" in french where "octet"=byte.

>>2 processes killed (possibly by Open MPI)
>>Could this be a problem of maximum allowed message size? Or of
>No, Open MPI should allow scattering of arbitrary sized messages.
>Can you verify that your arguments to MPI_SCATTER are correct, such
>as buffer length, the receive sizes on the clients, etc.?

Actually this part of the the code works fine with another mpi
implementation for much larger messages...If it can help, here
are relevant parts of the codes.

INTEGER, PARAMETER :: nb_proc=4, master=0
INTEGER, PARAMETER :: message_size=1000
INTEGER, parameter :: part_array_size=message_size*nb_proc

  integer :: p_type
  real(KIND=8), dimension(3) :: POS
  real(KIND=8), dimension(3) :: VEL
  real(KIND=8) :: u
  real(KIND=8) :: star_age
  real(KIND=8) :: mass
  real(KIND=8) :: frac_mass1
  real(KIND=8) :: h
  real(KIND=8) :: dens

TYPE(PART), dimension(part_array_size) :: part_array

! Declaration of the MPI type for PART !

call MPI_TYPE_EXTENT(MPI_INTEGER,mpi_integer_length,mpi_err)
array_of_block_length(1:2) = (/1,12/)
array_of_types(1:2) = (/MPI_INTEGER,MPI_DOUBLE_PRECISION/)
array_of_displacement(1) = 0
array_of_displacement(2) = MPI_integer_length
call MPI_TYPE_CREATE_STRUCT(2,array_of_block_length,array_of_displacement &
call MPI_TYPE_COMMIT(MPI_part,mpi_err)

call MPI_TYPE_EXTENT(MPI_PART,mpi_part_length,mpi_err)

! The communication call...

< snip
Here sone code filling part_array with data

snip >

call MPI_SCATTER(part_array,nb_sent,MPI_PART,MPI_IN_PLACE,nb_sent, &

( I ensure nb_send <= message_size)

>Are any corefiles generated? Do you know which processes die?
Yes, it generates one core file in this case (message_size=1000). And in
this case with 4 processes, 3 die:
"3 processes killed (possibly by Open MPI)"