softclock swis not bound to specific cpu
Ivan Voras
ivoras at freebsd.org
Mon Oct 19 15:15:16 UTC 2009
Robert Watson wrote:
>
> On Sun, 18 Oct 2009, Taku YAMAMOTO wrote:
>
>> I noticed that the softclock threads didn't seem to be bound to any cpu.
>>
>> I'm not sure whether it's the Right Thing (TM) to bind them to the
>> corresponding cpus though: it might be good to give the scheduler a
>> chance to rebalance callouts.
>>
>> I'm about to test the modification like the attached diff. Comments
>> are welcome.
>
> Yes, I think the intent is that they have a "soft" affinity to the CPU
> where the lapic timer is firing, but not a hard binding, allowing them
> to migrate if required. It would be interesting to measure how
> effective that soft affinity is in practice under various loads --
> presumably the goal would be for the softclock thread to migrate if a
> higher (lower) priority thread is hogging the CPU.
So why are there NCPU softclock threads if the binding isn't important?
More information about the freebsd-current
mailing list