devide core into cache.

so   30/12 = 2.5   this works  since the 2.5 is bigger then 2 by just a bit

joblo> this is a good match.

and

45/4 = 11.25   this works less since 11.25 is way bigger then   2

you can set threads used lower

if  you have say 40mb and 32 cores that is

40/32 = 1.25  this is under 2

so you would set this to

20 of the 32 cores

joblo> you have more cache than the  cores can use, need morecore with this much cache


and get

40/20 = 2

get cheap cpu's with big cache