% 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