% mpicc -o memcpy memcpy.c % mpirun -np 1 memcpy Size (bytes) Time (sec) Rate (MB/sec) 4 0.000001 4.827828 8 0.000001 5.596989 16 0.000001 23.608570 32 0.000001 29.409602 64 0.000001 47.214353 128 0.000002 57.191879 256 0.000004 63.481823 512 0.000008 67.216675 1024 0.000015 69.189189 2048 0.000029 69.429764 4096 0.000059 69.375240 8192 0.000522 15.699752 16384 0.001047 15.644162 32768 0.002087 15.699126 65536 0.004338 15.108003 131072 0.008378 15.644784 262144 0.016776 15.626133 524288 0.033448 15.674719 1048576 0.078048 13.435014 2097152 0.204210 10.269585