Does anyone know a good link that explains how to setup jtr to use multiple cores? I found some links but they were a few years old. Considering I have the latest version (1.7.9) I just wanted to make sure I didn't break jtr by using info for an older version. Multiple cores are nice, but if I break it, 0 cores are bad

I'm running backtrack 5 r1 x64.
I tried using hashcat, and while it uses multiple cores and is very fast by default, it was only able to crack 1/3 hashes, whereas john was able to crack all 3 using the --rules option with its default rules. So if anyone knows a good rules file for hashcat (and maybe a tutorial), that would be useful as well.
Thanks.