Take the 2-minute tour ×
Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

On my machine using a normal hard drive, a sum -s on a 5 GB file takes 2 seconds, while sum -r takes 5.5 seconds.

   -r     use BSD sum algorithm, use 1K blocks

   -s, --sysv
          use System V sum algorithm, use 512 bytes blocks

How can this be? I would expect larger blocks to perform better!

share|improve this question
add comment

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.