MPI Rank, OpenMP Thread ID, Core ID

.gitignore

omp_id

Makefile

CC = mpicc
C_OPT ?= -fopenmp

.PHONY: all
all: omp_id

omp_id: omp_id.c Makefile
	$(CC) $(C_OPT) -o $@ $<

omp_id.c

#define _GNU_SOURCE // sched_getcpu(3) is glibc-specific (see the man page)

#include <stdio.h>
#include <mpi.h>
#include <sched.h>
#include <omp.h>

int main(int argc, char** argv) {
    MPI_Init(NULL, NULL);
    
    int world_size;
    MPI_Comm_size(MPI_COMM_WORLD, &world_size);
    int world_rank;
    MPI_Comm_rank(MPI_COMM_WORLD, &world_rank);

#pragma omp parallel
    {
        int thread_num = omp_get_thread_num();
        int cpu_num = sched_getcpu();
        printf("MPI Rank: %3d, OpenMP Thread ID: %3d, Physical CPU ID: %3d\n", world_rank, thread_num, cpu_num);
    }

    MPI_Finalize();
    return 0;
}