Intel® MPI Library

Developer Guide for Linux* OS

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ID 768728
Date 10/31/2024
Public
Document Table of Contents
Document Table of Contents x
Developer Guide for Linux* OS
Developer Guide for Linux* OS x
Introduction Installation and Prerequisites Compiling and Linking Running Applications Debugging Applications Analysis and Tuning Troubleshooting Additional Supported Features Examples Notices and Disclaimers
Introduction x
Introducing Intel® MPI Library Conventions and Symbols Related Information
Installation and Prerequisites x
Installation Prerequisite Steps
Compiling and Linking x
Compiling an MPI Program Compilers Support ILP64 Support
Running Applications x
Running Intel® MPI Library in Containers Selecting a Library Configuration Running an MPI Program Running an MPI/OpenMP* Program MPMD Launch Mode Fabrics Control Job Schedulers Support Controlling Process Placement Java* MPI Applications Support
Running Intel® MPI Library in Containers x
Build a Singularity* Container for an MPI Application Run the Application with a Container
Fabrics Control x
Selecting Fabrics Libfabric* Support OFI* Providers Support
Debugging Applications x
Debugging Using -gtool for Debugging
Analysis and Tuning x
Displaying MPI Debug Information Tracing Applications Interoperability with Other Tools Through -gtool MPI Tuning
Troubleshooting x
Error Message: Bad Termination Error Message: No such file or Directory Error Message: Permission Denied Error Message: Fatal Error Error Message: Bad File Descriptor Error Message: Too Many Open Files Problem: High Memory Consumption Readings Problem: MPI Application Hangs Problem: Password Required Problem: Cannot Execute Binary File Problem: MPI limitation for Docker*
Additional Supported Features x
Asynchronous Progress Control Device-Initiated Communications Notified One-Sided Communications Multiple Endpoints Support
Multiple Endpoints Support x
MPI_THREAD_SPLIT Programming Model Threading Runtimes Support Program Examples pthreads - Explicit Submodel OpenMP Runtime - Implicit Submodel OpenMP Tasks - Explicit Submodel Code Change Guide
Examples x
async_progress_sample.c thread_split.cpp thread_split_omp_for.c thread_split_omp_task.c thread_split_pthreads.c
Developer Guide for Linux* OS

Program Examples

pthreads - Explicit Submodel

#include <mpi.h> 
#include <pthread.h> 
#define n 2 
int thread_id[n]; 
MPI_Comm split_comm[n]; 
pthread_t thread[n]; 
void *worker(void *arg) { 
    int i = *((int*)arg), j = i; 
    MPI_Comm comm = split_comm[i]; 
    MPI_Allreduce(MPI_IN_PLACE, &j, 1, MPI_INT, MPI_SUM, comm); 
    printf("Thread %d: allreduce returned %d\n", i, j); 
} 
int main() { 
    MPI_Info info; 
    int i, provided; 
    char s[16]; 
    MPI_Init_thread(NULL, NULL, MPI_THREAD_MULTIPLE, &provided); 
    MPI_Info_create(&info); 
    for (i = 0; i < n; i++) { 
        MPI_Comm_dup(MPI_COMM_WORLD, &split_comm[i]); 
        sprintf(s, "%d", i); 
        MPI_Info_set(info, "thread_id", s); 
        MPI_Comm_set_info(split_comm[i], info); 
        thread_id[i] = i; 
        pthread_create(&thread[i], NULL, worker, (void*) &thread_id[i]); 
    } 
    for (i = 0; i < n; i++) { 
        pthread_join(thread[i], NULL); 
    } 
    MPI_Info_free(&info); 
    MPI_Finalize(); 
}

OpenMP Runtime - Implicit Submodel

#include <mpi.h> 
#include <omp.h> 
#define n 2 
MPI_Comm split_comm[n]; 
int main() { 
    int i, provided; 
    MPI_Init_thread(NULL, NULL, MPI_THREAD_MULTIPLE, &provided); 
    for (i = 0; i < n; i++) 
        MPI_Comm_dup(MPI_COMM_WORLD, &split_comm[i]);                                                    
#pragma omp parallel for num_threads(n) 
    for (i = 0; i < n; i++) { 
        int j = i; 
        MPI_Allreduce(MPI_IN_PLACE, &j, 1, MPI_INT, MPI_SUM, split_comm[i]); 
        printf("Thread %d: allreduce returned %d\n", i, j); 
    } 
    MPI_Finalize(); 
}

OpenMP Tasks - Explicit Submodel

#include <mpi.h>
#include <omp.h>
#define n 2
MPI_Comm split_comm[n];
int main() {
    MPI_Info info;
    int i, provided;
    char s[16];
    MPI_Init_thread(NULL, NULL, MPI_THREAD_MULTIPLE, &provided);
    MPI_Info_create(&info);
    for (i = 0; i < n; i++) {
        MPI_Comm_dup(MPI_COMM_WORLD, &split_comm[i]);
        sprintf(s, "%d", i);
        MPI_Info_set(info, "thread_id", s);
        MPI_Comm_set_info(split_comm[i], info);
    }
#pragma omp parallel num_threads(n)
    {
#pragma omp task
        {
            int j = 1;
            MPI_Allreduce(MPI_IN_PLACE, &j, 1, MPI_INT, MPI_SUM, split_comm[1]);
            printf("OMP thread %d, logical thread %d: allreduce returned %d\n",
                    omp_get_thread_num(), 1, j);
        }
#pragma omp task
        {
            int j = 0;
            MPI_Allreduce(MPI_IN_PLACE, &j, 1, MPI_INT, MPI_SUM, split_comm[0]);
            printf("OMP thread %d, logical thread %d: allreduce returned %d\n",
                    omp_get_thread_num(), 0, j);
        }
    }
    MPI_Info_free(&info);
    MPI_Finalize();
}
Parent topic: Multiple Endpoints Support
Level Two Title