On Sat, Jun 5, 2010 at 2:44 PM, David Zhang <solarbik...@gmail.com> wrote:
> Dear all: > > I'm using mpi_iprobe to serve as a way to send signals between different > mpi executables. I'm using the following test codes (fortran): > > #1 > program send > implicit none > include 'mpif.h' > > real*8 :: vec(20000)=1.0 > integer :: ierr,i=0,request(1) > > call mpi_init(ierr) > do > call mpi_isend(vec,20000,mpi_real8, > 0,1,mpi_comm_world,request(1),ierr) > i=i+1 > print *,i > vec=-vec > call usleep_fortran(2.d0) > call mpi_wait(request(1),MPI_STATUS_IGNORE,ierr) > end do > > end program send > -------------------------------------------------- > #2 > program send > implicit none > include 'mpif.h' > > real*8 :: vec(20000) > integer :: ierr > > call mpi_init(ierr) > do > if(key_present()) then > call > mpi_recv(vec,20000,mpi_real8,1,1,mpi_comm_world,MPI_STATUS_IGNORE,ierr) > end if > call usleep_fortran(0.05d0) > > end do > > contains > > function key_present() > implicit none > logical :: key_present > > key_present = .false. > call > mpi_iprobe(1,1,mpi_comm_world,key_present,MPI_STATUS_IGNORE,ierr) > print *, key_present > > end function key_present > > end program send > ----------------------------------- > The usleep_fortran is a routine I've written to pause the program for that > amount of time (in seconds). As you can see, on the receiving end I'm > probing to see whether the message has being received every 0.05 seconds, > where each probing would result a print of the probing result; while the > sending is once every 2 seconds. > > Doing > mpirun -np 1 recv : -np 1 send > Naturally I expect the output to be something like: > > 1 > (fourty or so F) > T > 2 > (another fourty or so F) > T > 3 > > however this is the output I get: > > 1 > (fourty or so F) > T > 2 > (about a two second delay) > T > 3 > > It seems to me that after the first set of probes, once the message was > received, the non-blocking mpi probe becomes blocking for some strange > reason. I'm using mpi_iprobe for the first time, so I'm not sure if I'm > doing something blatantly wrong. > > > -- > David Zhang > University of California, San Diego > -- David Zhang University of California, San Diego
