% mpicc -o memcpy memcpy.c
% mpirun -np 1 memcpy
Size (bytes) Time (sec)	Rate (MB/sec)
4	0.000001	4.647218
8	0.000001	5.601300
16	0.000002	10.177081
32	0.000002	17.395842
64	0.000003	25.467974
128	0.000004	33.239156
256	0.000007	39.369105
512	0.000012	43.057177
1024	0.000023	45.335452
2048	0.000045	45.320018
4096	0.000324	12.631927
8192	0.000279	29.386145
16384	0.000553	29.605180
32768	0.001106	29.631952
65536	0.002214	29.598495
131072	0.004425	29.618560
262144	0.008847	29.630835
524288	0.017676	29.661009
1048576	0.035314	29.692926
2097152	0.070625	29.694188