bitcnts是mibench众多测试软件中的一个,但足够测试CPU的性能
下面贴上SEP4020+Linux2.6上跑1000000位测试时间
测试环境CPU88MHz 开LCD NFS网络文件系统

/mibench/bitcount # ./bitcnts.arm   1000000
Bit counter algorithm benchmark

Optimized 1 bit/loop counter       > Time: 1.880 sec.; Bits: 16574990
Ratko’s mystery algorithm          > Time: 0.980 sec.; Bits: 15358803
Recursive bit count by nybbles        > Time: 4.130 sec.; Bits: 15309077
Non-recursive bit count by nybbles > Time: 1.070 sec.; Bits: 16253383
Non-recursive bit count by bytes (BW) > Time: 0.770 sec.; Bits: 16617466
Non-recursive bit count by bytes (AR) > Time: 0.980 sec.; Bits: 15233906
Shift and count bits                > Time: 6.000 sec.; Bits: 15691122

Best   > Non-recursive bit count by bytes (BW)
Worst > Shift and count bits

1000000位的测试就慢了很多

/mibench/bitcount # ./bitcnts.arm 10000000
Bit counter algorithm benchmark

Optimized 1 bit/loop counter       > Time:   18.620 sec.; Bits: 164838829
Ratko’s mystery algorithm          > Time: 9.740 sec.; Bits: 158063216
Recursive bit count by nybbles        > Time:   41.150 sec.; Bits: 160571544
Non-recursive bit count by nybbles > Time:   10.630 sec.; Bits: 162707129
Non-recursive bit count by bytes (BW) > Time: 7.640 sec.; Bits: 170893188
Non-recursive bit count by bytes (AR) > Time: 9.790 sec.; Bits: 154106854
Shift and count bits                > Time:   59.870 sec.; Bits: 154959757

Best   > Non-recursive bit count by bytes (BW)
Worst > Shift and count bits
/mibench/bitcount #