ULE Scheduler

[Daniel Kalchev]

On 07.06.12 11:16, Momchil Ivanov wrote:
> Though, it was strange seeing both processes hopping around... I will 
> probably go back to the 4BSD scheduler if my laptop does another 
> self-shutdown in the next few days as Doug suggested.

You never run just two processes on FreeBSD, ever. The kernel too runs 
multiple threads.

However small the CPU usage of the other processes is, they must run 
from time to time, kicking out at least one of your CPU intensive 
processes, possibly kicking them out both, as well. When that happens, 
and they are queued to run again it does not matter much on which core 
they ran before, because chances are it's cache will be invalidated 
anyway. Also, different CPUs have different cache affinity. ULE is 
supposed to be aware of this, while the 4BSD scheduler is not.

In any case, on an older single/dual core CPU there is rarely any 
difference between both schedulers. Differences might appear in modern 
multi-core CPUs..

Daniel