CPU Competition Issue

[Steven Nikkel]

On Tue, 30 Oct 2012, Andriy Gapon wrote:
>> I'm running a long duration CPU-centric process that will gobble up all
>> available CPU time. I have it set to run at nice +20. While it's running I've
>> noticed other processes have a hard time getting CPU time and run their
>> activites very slowly. The processes I've noticed issues with are IO involved,
>> but they don't appear to be IO blocked as they run dramatically faster and use
>> much more CPU time when the CPU intensive process is not running. I haven't
>> noticed issues with other processes, but I haven't been looking. If I push my
>> CPU intensive process into idle priority 1, all the other processes return to
>> their normal behaviour as if it's not running.
>>
>> This seems to be a specific behaviour on this one machine running 9.0-RELEASE-p4
>> on an Atom 330 dual core. I've tried with and without hyperthreading enabled
>> with no noticeable change in behaviour.
>
> Can you try with lower nice value, like +10?
> You want a fix from r228718.  AFAIR, it is not in 9.0.
>

They seem to share in a much more reasonable manor after assigning the 
process to +10 instead of +20, which sounds like the fix you mentioned. 
The process hits priorities in the 120s when its competing. I think I'll 
continue with idle priority as that obtains the sharing behaviour I'm 
after.