[mpich-discuss] nonblocking collectives, progress thread

[Pieter Ghysels]

Dear,

I'm replacing calls to MPI_Allreduce by calls to MPIX_Iallreduce. 
I'm compiling with -mpe=mpilog and look at the communication pattern
with jumpshot. The MPI_Allreduce's are gone now of course, but
mpe/jumpshot does not show MPIX_Iallreduce. Instead, where the
MPI_Allreduce used to be, now a lot of time is being spent in
MPI_Win_create and MPI_Win_free, where before the MPI_Allreduce was
taking place. Is this normal?

Can I configure MPICH2 to use a progress thread for the nonblocking
collectives, as in libNBC?
Do I have to use MPI_Init_thread()?

Pieter