Synergy User Manual and Tutorial. - THE CORE MEMORY

Synergy User Manual and Tutorial
MPI_Finalize();
which disables the MPI interface. To compile and run an MPI application type:
[c615111@owin ~/mpi ]>mpicc -o hello hello.c
[c615111@owin ~/mpi ]>mpirun –np 4 hello
The mpirun command activates a MPI application named “hello” with 4 processes (1
master and 3 workers) and the mpicc command is actually not a proprietary compiler. It
is a definition that is equivalent a call to the cc compiler with the following arguments to
access the proper libraries:
[c615111@owin ~/mpi ]>cc -o hello hello.c -I/usr/local/mpi/include\
-L/usr/local/mpi/lib -lmpi
An example of an MPI application is:
// hello.c program
#include
#include “mpi.h”
main(int argc, char** argv){
int my_rank;
int p;
int source;
int dest;
int tag = 50;
char buf[100];
MPI_Status status;
FILE* fd;
// Rank of process
// Number of processes
// Rank of sender in loops
// Rank of receiver
// Tag for messages
// Storage buffer for the message
// Return status for receive
// File in which to write master’s message
// Open file to store message
fd = fopen(“msg.txt”, "a");
// Get host machine name
gethostname(host, sizeof(host));
// Initialize MPI application session
// No MPI functions may be used until this is called
// This function may only be called once
MPI_Init(&argc, &argv);
// Get my rank
// Master’s rank will be ‘0’
// Worker’s ranks will be greater than ‘0’
MPI_Comm_rank(MPI_COMM_WORLD, &my_rank);
// Get the number of running processes
MPI_Comm_size(MPI_COMM_WORLD, &p);
// If my_rank != 0, I am a worker
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