Hi Matteo,
> If not using an HW crypto engine, the code doesn't have locks, but I
> tried it anyway on a quad core machine:
>
> $ time ./sha1sum 2g.bin
> 752ef2367f479e79e4f0cded9c270c2890506ab0 2g.bin
>
> real 0m2.198s
> user 0m0.000s
> sys 0m2.198s
> $ for i in {1..4}; do time ./sha1sum 2g.bin & done
> [1] 27893
> [2] 27894
> [3] 27896
> [4] 27897
> 752ef2367f479e79e4f0cded9c270c2890506ab0 2g.bin
>
> real 0m2.367s
> user 0m0.001s
> sys 0m2.367s
> 752ef2367f479e79e4f0cded9c270c2890506ab0 2g.bin
>
> real 0m2.374s
> user 0m0.000s
> sys 0m2.365s
> 752ef2367f479e79e4f0cded9c270c2890506ab0 2g.bin
>
> real 0m2.383s
> user 0m0.001s
> sys 0m2.383s
> 752ef2367f479e79e4f0cded9c270c2890506ab0 2g.bin
>
> real 0m2.383s
> user 0m0.001s
> sys 0m2.382s
>
> [1] Done time ./sha1sum 2g.bin
> [2] Done time ./sha1sum 2g.bin
> [3]- Done time ./sha1sum 2g.bin
> [4]+ Done time ./sha1sum 2g.bin
So there is no bottleneck here. Perfect.
> If you're using an HW crypto engine, locking can happen depending on
> how the hardware works, but such chips can be 100x faster than CPUs so
> it's not an issue.
This is understandable. Should be a win anyway, even with a small number
of processes or threads operating in parallel.
Thanks for the clarifications!
Bruno
