Tim wrote:
Hi,
I am learning MPI on a cluster. Here is one simple example. I expect the output would show response from different nodes, but they all respond from the same node node062. I just wonder why and how I can actually get report from different nodes to show MPI actually distributes processes to different nodes? Thanks and regards!
ex1.c
/* test of MPI */
#include "mpi.h"
#include <stdio.h>
#include <string.h>
int main(int argc, char **argv)
{
char idstr[2232]; char buff[22128];
char processor_name[MPI_MAX_PROCESSOR_NAME];
int numprocs; int myid; int i; int namelen;
MPI_Status stat;
MPI_Init(&argc,&argv);
MPI_Comm_size(MPI_COMM_WORLD,&numprocs);
MPI_Comm_rank(MPI_COMM_WORLD,&myid);
MPI_Get_processor_name(processor_name, &namelen);
if(myid == 0)
{
printf("WE have %d processors\n", numprocs);
for(i=1;i<numprocs;i++)
{
sprintf(buff, "Hello %d", i);
MPI_Send(buff, 128, MPI_CHAR, i, 0, MPI_COMM_WORLD); }
for(i=1;i<numprocs;i++)
{
MPI_Recv(buff, 128, MPI_CHAR, i, 0, MPI_COMM_WORLD, &stat);
printf("%s\n", buff);
}
}
else
{
MPI_Recv(buff, 128, MPI_CHAR, 0, 0, MPI_COMM_WORLD, &stat);
sprintf(idstr, " Processor %d at node %s ", myid, processor_name);
strcat(buff, idstr);
strcat(buff, "reporting for duty\n");
MPI_Send(buff, 128, MPI_CHAR, 0, 0, MPI_COMM_WORLD);
}
MPI_Finalize();
}
ex1.pbs
#!/bin/sh
#
#This is an example script example.sh
#
#These commands set up the Grid Environment for your job:
#PBS -N ex1
#PBS -l nodes=10:ppn=1,walltime=1:10:00
#PBS -q dque
# export OMP_NUM_THREADS=4
mpirun -np 10 /home/tim/courses/MPI/examples/ex1
Try running your program with the following:
mpirun -np 10 -machinefile machines /home/tim/courses/MPI/examples/ex1
where 'machines' is a file containing the names of your nodes (one per line)
node063
node064
...
node177
HTH,
--
Constantinos Makassikis
compile and run:
[tim@user1 examples]$ mpicc ./ex1.c -o ex1
[tim@user1 examples]$ qsub ex1.pbs
35540.mgt
[tim@user1 examples]$ nano ex1.o35540
----------------------------------------
Begin PBS Prologue Sat Jan 30 21:28:03 EST 2010 1264904883
Job ID: 35540.mgt
Username: tim
Group: Brown
Nodes: node062 node063 node169 node170 node171 node172 node174 node175
node176 node177
End PBS Prologue Sat Jan 30 21:28:03 EST 2010 1264904883
----------------------------------------
WE have 10 processors
Hello 1 Processor 1 at node node062 reporting for duty
Hello 2 Processor 2 at node node062 reporting for duty
Hello 3 Processor 3 at node node062 reporting for duty
Hello 4 Processor 4 at node node062 reporting for duty
Hello 5 Processor 5 at node node062 reporting for duty
Hello 6 Processor 6 at node node062 reporting for duty
Hello 7 Processor 7 at node node062 reporting for duty
Hello 8 Processor 8 at node node062 reporting for duty
Hello 9 Processor 9 at node node062 reporting for duty
----------------------------------------
Begin PBS Epilogue Sat Jan 30 21:28:11 EST 2010 1264904891
Job ID: 35540.mgt
Username: tim
Group: Brown
Job Name: ex1
Session: 15533
Limits: neednodes=10:ppn=1,nodes=10:ppn=1,walltime=01:10:00
Resources: cput=00:00:00,mem=420kb,vmem=8216kb,walltime=00:00:03
Queue: dque
Account:
Nodes: node062 node063 node169 node170 node171 node172 node174 node175 node176
node177
Killing leftovers...
End PBS Epilogue Sat Jan 30 21:28:11 EST 2010 1264904891
----------------------------------------
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