[mpich-discuss] nonblocking collectives, progress thread

[Pieter Ghysels]

Ah, yes, sorry for the confusion. I am also overlapping the
MPIX_Iallreduce with other (one-sided) MPI calls. But these calls are
buried in the library I use, and I'm not so familiar with one sided
communication. But I was told that there are no calls to MPI_Win_create
or MPI_Win_free, except at the very beginning and end of the program.

Is it possible to overlap different MPI calls like that? 

I configured MPICH2 with 
--enable-threads=runtime
and initialized with 
MPI_Init_thread(argc, argv, MPI_THREAD_MULTIPLE, &thread_support);


Pieter

On Fri, 2012-04-06 at 19:27 -0500, Jeff Hammond wrote:
> One way to implement nonblocking allreduce would be to use
> MPI_Accumulate, so it doesn't seem entirely nuts.  I presume you know
> the MPICH2 implementation of MPIX_Iallreduce does not use RMA...
> 
> Jeff
> 
> On Fri, Apr 6, 2012 at 6:24 PM, Rajeev Thakur <thakur at mcs.anl.gov> wrote:
> > You mean your program doesn't call MPI_Win_create and MPI_win_free but Jumpshot shows them? No, that's not normal.
> >
> > Rajeev
> >
> > On Apr 6, 2012, at 3:14 PM, Pieter Ghysels wrote:
> >
> >> 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
> >>
> >> _______________________________________________
> >> mpich-discuss mailing list     mpich-discuss at mcs.anl.gov
> >> To manage subscription options or unsubscribe:
> >> https://lists.mcs.anl.gov/mailman/listinfo/mpich-discuss
> >
> > _______________________________________________
> > mpich-discuss mailing list     mpich-discuss at mcs.anl.gov
> > To manage subscription options or unsubscribe:
> > https://lists.mcs.anl.gov/mailman/listinfo/mpich-discuss
> 
> 
>