Re: [mpich-discuss] where mpi waitsome only returns one request each time

19 Oct 2014


      Try to run on another machine, you may get different results. My configure
is
$ mpichversion
MPICH Version:     3.1.3
MPICH Release date: unreleased development copy
MPICH Device:     ch3:nemesis
MPICH configure: --enable-romio --enable-nemesis-dbg-localoddeven
--enable-g=all --enable-fast=O0 --enable-fortran=f77,fc CC=gcc CXX=g++
F77=gfortran FC=gfortran
MPICH CC: gcc    -g -O0
MPICH CXX: g++   -g -O0
MPICH F77: gfortran   -g -O0
MPICH FC: gfortran   -g -O0

--Junchao Zhang

On Sun, Oct 19, 2014 at 9:23 PM, myself <[email protected]> wrote:
...
I run several times of the program, the results are as the same as before. Could
you tell me your MPICH version and compiling parameters? The version of
my MPICH is 3.1.3, I compile it as
$ mpirun --version
HYDRA build details:
    Version:                                 3.1.3
    Release Date:                            Wed Oct  8 09:37:19 CDT 2014
    CC:                              gcc  -fPIC
    CXX:                             g++
    F77:                             gfortran
    F90:                             gfortran
    Configure options:                       '--disable-option-checking'
'--prefix=/usr/local/mpich3' '--with-device=ch3:nemesis' 'CFLAGS=-fPIC -O2'
'--disable-fortran' '--cache-file=/dev/null' '--srcdir=.' 'CC=gcc'
'LDFLAGS= ' 'LIBS=-lpthread ' 'CPPFLAGS=
-I/home/valder/Downloads/Software/mpi/mpich-3.1.3/src/mpl/include
-I/home/valder/Downloads/Software/mpi/mpich-3.1.3/src/mpl/include
-I/home/valder/Downloads/Software/mpi/mpich-3.1.3/src/openpa/src
-I/home/valder/Downloads/Software/mpi/mpich-3.1.3/src/openpa/src
-D_REENTRANT
-I/home/valder/Downloads/Software/mpi/mpich-3.1.3/src/mpi/romio/include'
    Process Manager:                         pmi
    Launchers available:                     ssh rsh fork slurm ll lsf sge
manual persist
    Topology libraries available:            hwloc
    Resource management kernels available:   user slurm ll lsf sge pbs
cobalt
    Checkpointing libraries available:
    Demux engines available:                 poll select
the whole program is
=========
#include "mpi.h"
#include <stdio.h>
#include <stdlib.h>
#include <sys/time.h>
typedef unsigned char byte;
int main(int argc, char *argv[]){
    int rank,size;
    byte buf[10][10];
    MPI_Request req[10];
    MPI_Status stat[10];
    int outcount;
    int array_of_indices[10];
    int i;
    int complete = 0;
MPI_Init(&argc, &argv);
    MPI_Comm_size(MPI_COMM_WORLD, &size);
    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
if(rank==0) {
        for(i =0; i< 10;i++){
            MPI_Isend(buf[i], 10, MPI_BYTE, 1, 123, MPI_COMM_WORLD,
&req[i]);
        }
        printf("post send\n");
    }else {
        for(i=0; i< 10;i++){
            MPI_Irecv(buf[i], 10, MPI_BYTE, 0, 123, MPI_COMM_WORLD,
&req[i]);
        }
        printf("post recv\n");
    }
for (;;){
        MPI_Waitsome(10, req, &outcount, array_of_indices, stat);
        complete += outcount;
        printf("rank %d %d index %d\n", rank, outcount,
array_of_indices[0]);
        if(complete == 10)
            break;
    }
    printf("rank %d complete\n", rank);
    MPI_Finalize();
}
=========
I compile it as
$ mpicc -o tests testsome.c
and run as
$ mpirun -n 2 ./tests
At 2014-10-20 09:02:39, "Junchao Zhang" <[email protected]> wrote:
I think it is random. For example, I ran your code and its output was:
post recv
post send
rank 0 10 index 0
rank 0 complete
rank 1 1 index 0
rank 1 9 index 1
rank 1 complete
--Junchao Zhang
On Sun, Oct 19, 2014 at 9:48 AM, myself <[email protected]> wrote:
...
Because I want to understand the behavior of MPI_Waitsome, I change the
program as fellow. MPI can waitsome 10 Isend request once time, while
waitsome 1 Irecv request each time. Why waitsome-Irecv can not be more than
1 as I expect?
=====
     MPI_Init(&argc, &argv);
     MPI_Comm_size(MPI_COMM_WORLD, &size);
     MPI_Comm_rank(MPI_COMM_WORLD, &rank);
if(rank==0) {
         for(i =0; i< 10;i++){
             MPI_Isend(buf[i], 10, MPI_BYTE, 1, 123, MPI_COMM_WORLD,
&req[i]);
         }
         printf("post send\n");
     }else {
         for(i=0; i< 10;i++){
             MPI_Irecv(buf[i], 10, MPI_BYTE, 0, 123, MPI_COMM_WORLD,
&req[i]);
         }
         printf("post recv\n");
     }
for (;;){
         MPI_Waitsome(10, req, &outcount, array_of_indices, stat);
         complete += outcount;
         printf("rank %d %d index %d\n", rank, outcount,
array_of_indices[0]);
         if(complete == 10)
             break;
     }
     printf("rank %d complete\n", rank);
     MPI_Finalize();
=====
$ mpirun -n 2 ./tests
post send
post recv
rank 0 10 index 0
rank 0 complete
rank 1 1 index 0
rank 1 1 index 1
rank 1 1 index 2
rank 1 1 index 3
rank 1 1 index 4
rank 1 1 index 5
rank 1 1 index 6
rank 1 1 index 7
rank 1 1 index 8
rank 1 1 index 9
rank 1 complete
At 2014-10-19 22:36:25, "Bland, Wesley B." <[email protected]> wrote:
You need to move your waitany outside of the if statement so both ranks
execute it.
On Oct 19, 2014, at 9:33 AM, myself <[email protected]> wrote:
Here is my test program
======
#include "mpi.h"
 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/time.h>
typedef unsigned char byte;
int main(int argc, char *argv[]){
     MPI_Init(&argc, &argv);
     int rank,size;
     MPI_Comm_size(MPI_COMM_WORLD, &size);
     MPI_Comm_rank(MPI_COMM_WORLD, &rank);
     byte buf[10][10];
     MPI_Request req[10];
     MPI_Status stat[10];
     int outcount;
     int array_of_indices[10];
     int i;
if(rank==0) {
         for(i =0; i< 10;i++){
             MPI_Isend(buf[i], 10, MPI_BYTE, 1, 123, MPI_COMM_WORLD,
&req[i]);
         }
         printf("post send\n");
         MPI_Waitall(10, req, stat);
         printf("send over\n");
     }else {
         for(i=0; i< 10;i++){
             MPI_Irecv(buf[i], 10, MPI_BYTE, 0, 123, MPI_COMM_WORLD,
&req[i]);
         }
printf("post recv\n");
         for (i=0;i<10;i++){
             MPI_Waitsome(10, req, &outcount, array_of_indices, stat);
             printf("%d index %d\n", outcount, array_of_indices[0]);
         }
     }
     MPI_Finalize();
 }
======
 get the result like this
======
 $ mpirun -n 2 ./tests
post send
send over
post recv
1 index 0
1 index 1
1 index 2
1 index 3
1 index 4
1 index 5
1 index 6
1 index 7
1 index 8
1 index 9
======
I think I should get some completed receive connection, not just 1.
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Junchao Zhang

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