On rank 0 you're opening the file N-1 times and closing it once. This
isn't your problem (I will leave that to others), but you should
probably fix that in your code. Might be buffering and not writing.
Rob
On May 13, 2008, at 2:32 PM, Davi Vercillo C. Garcia wrote:
Hi all,
I'm trying to run some programs using MPI-IO, like MPI-IO Test, and
I'm with some problems. Trying to discover what is happening, I build
a simple distributed IO program with MPI and "fprintf" function, like
above, but the output is not correctly when is executed in PVFS.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "mpi.h"
int main(int argc, char** argv) {
int my_rank; /* Rank of process */
int p; /* Number of processes */
int source; /* Rank of sender */
int dest; /* Rank of receiver */
int tag = 50; /* Tag for messages */
char message[100]; /* Storage for the message */
MPI_Status status; /* Return status for receive */
MPI_Init(&argc, &argv);
MPI_Comm_rank(MPI_COMM_WORLD, &my_rank);
MPI_Comm_size(MPI_COMM_WORLD, &p);
FILE *pfile;
if (my_rank != 0) {
sprintf(message, "Greetings from process %d!", my_rank);
dest = 0;
pfile = fopen("teste.txt","w");
/* Use strlen(message)+1 to include '\0' */
MPI_Send(message, strlen(message)+1, MPI_CHAR, dest, tag,
MPI_COMM_WORLD);
} else { /* my_rank == 0 */
for (source = 1 ; source < p ; source++) {
MPI_Recv(message, 100, MPI_CHAR, source, tag,
MPI_COMM_WORLD, &status);
pfile = fopen("teste.txt","a");
fprintf(pfile,"%s\n", message);
}
}
fclose(pfile);
MPI_Finalize();
return 0;
} /* main */
When i execute him with 25 nodes on NFS, the output is:
Greetings from process 24!
Greetings from process 23!
Greetings from process 22!
Greetings from process 21!
Greetings from process 20!
Greetings from process 19!
Greetings from process 18!
Greetings from process 17!
Greetings from process 16!
Greetings from process 15!
Greetings from process 14!
Greetings from process 13!
Greetings from process 12!
Greetings from process 11!
Greetings from process 10!
Greetings from process 9!
Greetings from process 8!
Greetings from process 7!
Greetings from process 6!
Greetings from process 5!
Greetings from process 4!
Greetings from process 3!
Greetings from process 2!
Greetings from process 1!
But with PVFS, is only:
Greetings from process 1!
I'm using the last version of PVFS2 with 1 MDS and 3 IOS. The content
of file pvfs2tab is:
tcp://campogrande01:3334/pvfs2-fs /mnt/pvfs2 pvfs2 rw,user,noauto 0 0
Someone can help me, please ?!
--
Davi Vercillo Carneiro Garcia
Universidade Federal do Rio de Janeiro
Departamento de Ciência da Computação
DCC-IM/UFRJ - http://www.dcc.ufrj.br
"Good things come to those who... wait." - Debian Project
"A computer is like air conditioning: it becomes useless when you open
windows." - Linus Torvalds
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