测量小循环加速比

loop    body     serial parallel speedup   code
100*1, 100*1,  0.083,  0.01,    8.3          10k

100*2, 100*2,  0.33,  0.028,    12           40k
100*1, 100*4,  0.33,  0.035,    10
100*4, 100*1,  0.33,  0.029,    12

100*4, 100*4,   1.3,   0.11,     12          160k
100*1, 100*16,  1.3,   0.13,     10
100*16, 100*1,  1.3,   0.11,     12

100*8, 100*8,   5.4,   0.42,     13          640k
100*1, 100*64,  5.5,   0.52,     11
100*64, 100*1,  5.4,   0.43,     13
100*4, 100*16,  5.3,   0.42,     13
100*16, 100*4,  5.4,   0.43,     13

100*16, 100*16,  13,   1.7,     7.6         2.5m
100*1, 100*256,  12,   2.1,     5.7
100*256, 100*1,  13,   1.7,     7.6
100*4, 100*64,   13,   1.7,     7.6
100*64, 100*4,   13,   1.7,     7.6