The performance of the MPI Cholesky kernel is obtained by taking the

length of the longest process. We add barriers to ensure that the
measurement starts at the same time too.

mpi/examples/cholesky/mpi_cholesky.c

@@ -79,7 +79,6 @@ static void dw_cholesky(float ***matA, unsigned size, unsigned ld, unsigned nblo
         data_handles = malloc(nblocks*sizeof(starpu_data_handle *));
         for(x=0 ; x<nblocks ; x++) data_handles[x] = malloc(nblocks*sizeof(starpu_data_handle));
 
-	gettimeofday(&start, NULL);
         for(x = 0; x < nblocks ;  x++) {
                 for (y = 0; y < nblocks; y++) {
                         int mpi_rank = my_distrib(x, y, nodes);
@@ -103,6 +102,9 @@ static void dw_cholesky(float ***matA, unsigned size, unsigned ld, unsigned nblo
                 }
         }
 
+	starpu_mpi_barrier(MPI_COMM_WORLD);
+	gettimeofday(&start, NULL);
+
 	for (k = 0; k < nblocks; k++)
         {
                 int prio = STARPU_DEFAULT_PRIO;
@@ -151,14 +153,18 @@ static void dw_cholesky(float ***matA, unsigned size, unsigned ld, unsigned nblo
         }
 	free(data_handles);
 
+	starpu_mpi_barrier(MPI_COMM_WORLD);
 	gettimeofday(&end, NULL);
 
-	double timing = (double)((end.tv_sec - start.tv_sec)*1000000 + (end.tv_usec - start.tv_usec));
-	fprintf(stderr, "[%d] Computation took (in ms)\n", rank);
-	fprintf(stdout, "%2.2f\n", timing/1000);
-
-	double flop = (1.0f*size*size*size)/3.0f;
-	fprintf(stderr, "Synthetic GFlops : %2.2f\n", (flop/timing/1000.0f));
+	if (rank == 0)
+	{
+		double timing = (double)((end.tv_sec - start.tv_sec)*1000000 + (end.tv_usec - start.tv_usec));
+		fprintf(stderr, "Computation took (in ms)\n");
+		fprintf(stdout, "%2.2f\n", timing/1000);
+	
+		double flop = (1.0f*size*size*size)/3.0f;
+		fprintf(stderr, "Synthetic GFlops : %2.2f\n", (flop/timing/1000.0f));
+	}
 }
 
 int main(int argc, char **argv)
@@ -173,7 +179,13 @@ int main(int argc, char **argv)
 
 	parse_args(argc, argv);
 
-	starpu_init(NULL);
+	struct starpu_conf conf;
+	starpu_conf_init(&conf);
+	
+	conf.sched_policy_name = "heft";
+	conf.calibrate = 1;
+
+	starpu_init(&conf);
 	starpu_mpi_initialize_extended(&rank, &nodes);
 	starpu_helper_cublas_init();
 

mpi/examples/cholesky/mpi_cholesky_distributed.c

@@ -79,6 +79,7 @@ static void dw_cholesky(float ***matA, unsigned size, unsigned ld, unsigned nblo
         data_handles = malloc(nblocks*sizeof(starpu_data_handle *));
         for(x=0 ; x<nblocks ; x++) data_handles[x] = malloc(nblocks*sizeof(starpu_data_handle));
 
+	starpu_mpi_barrier(MPI_COMM_WORLD);
 	gettimeofday(&start, NULL);
         for(x = 0; x < nblocks ;  x++) {
                 for (y = 0; y < nblocks; y++) {
@@ -151,14 +152,18 @@ static void dw_cholesky(float ***matA, unsigned size, unsigned ld, unsigned nblo
         }
 	free(data_handles);
 
+	starpu_mpi_barrier(MPI_COMM_WORLD);
 	gettimeofday(&end, NULL);
 
-	double timing = (double)((end.tv_sec - start.tv_sec)*1000000 + (end.tv_usec - start.tv_usec));
-	fprintf(stderr, "[%d] Computation took (in ms)\n", rank);
-	fprintf(stdout, "%2.2f\n", timing/1000);
-
-	double flop = (1.0f*size*size*size)/3.0f;
-	fprintf(stderr, "Synthetic GFlops : %2.2f\n", (flop/timing/1000.0f));
+	if (rank == 0)
+	{
+		double timing = (double)((end.tv_sec - start.tv_sec)*1000000 + (end.tv_usec - start.tv_usec));
+		fprintf(stderr, "Computation took (in ms)\n");
+		fprintf(stdout, "%2.2f\n", timing/1000);
+	
+		double flop = (1.0f*size*size*size)/3.0f;
+		fprintf(stderr, "Synthetic GFlops : %2.2f\n", (flop/timing/1000.0f));
+	}
 }
 
 int main(int argc, char **argv)
@@ -173,7 +178,13 @@ int main(int argc, char **argv)
 
 	parse_args(argc, argv);
 
-	starpu_init(NULL);
+	struct starpu_conf conf;
+	starpu_conf_init(&conf);
+
+	conf.sched_policy_name = "heft";
+	conf.calibrate = 1;
+
+	starpu_init(&conf);
 	starpu_mpi_initialize_extended(&rank, &nodes);
 	starpu_helper_cublas_init();