MPIで大きなsize_tをMPI_UINT64_Tとして渡して、大きな配列を確保／初期化 (first touch) する。MPI_AINTまたはMPI_COUNTを使うべき？

large_array.c

// large_array.c
//        Gist: https://gist.github.com/t-nissie/38df694682cbdb08023567731f432fbf
// Description: pass a size_t as MPI_UINT64_T, allocate a large array of double, then first-touch it
//      Author: Takeshi Nishimatsu
//     License: GPLv3
//   Reference: https://github.com/jeffhammond/BigMPI/blob/master/test/test_reduce_x.c
////
#include <mpi.h>
#include <stdio.h>
#include <stdlib.h>
int main(int argc, char **argv)
{
  int     i_error, mpi_my_rank;
  double  start, finish;
  double  *ary;
  size_t N, i;
  i_error = MPI_Init(&argc,&argv);
  i_error = MPI_Comm_rank(MPI_COMM_WORLD, &mpi_my_rank);
  if (mpi_my_rank==0) {
    i_error = sscanf(argv[1],"%zu",&N);
  }
  MPI_Bcast(&N, 1, MPI_UINT64_T, 0, MPI_COMM_WORLD);
  ary = (double *) malloc(N*sizeof(double));
  if (ary==0) {
    i_error = MPI_Abort(MPI_COMM_WORLD, 1);
  }
  start  = MPI_Wtime();
  for (i=0; i<N; ++i) {
    ary[i] = 0.0;
  }
  finish = MPI_Wtime();
  printf("%3d %20zu %12.5f\n", mpi_my_rank, N, finish - start);
  i_error = MPI_Finalize();
}
//Local variables:
//compile-command: "mpicc -c large_array.c && mpicc -o large_array large_array.o && mpiexec -np 4 ./large_array 1000"
//End:

large_array.jcf

#!/usr/bin/csh -f
#@ job_name = 2G
#@ output = $(job_name).$(jobid).$(stepid).out
#@ error  = $(job_name).$(jobid).$(stepid).err
#@ notification = complete
#@ notify_user = t-nissie@example.com
#@ job_type = parallel
#@ total_tasks = 2
#@ stack_limit = 960mb
#@ task_affinity = cpu(1)
#@ cpus_per_core = 1
#@ queue
# Description: queuing script for SR16000
# Compilation: mpcc -c large_array.c && mpcc -o large_array large_array.o
# Usage: submit EJCF general -jcf large_array
##
poe ./large_array 2000000000

results.txt

==> 2G.441629.0.out <==
  1           2000000000      9.62017
  0           2000000000      9.64697

==> 4G.441630.0.out <==
  1           4000000000     19.24187
  0           4000000000     19.29837

==> 6G.441631.0.out <==
  1           6000000000     28.86055
  0           6000000000     28.94758

==> 7G.441632.0.out <==
  ---> error with exit code of 1
       maybe, out of memory