Re: Question on CONFIG_IRQBALANCE / 2.6.x

[Jeff Garzik <jgarzik@pobox.com>]

Joerg Sommrey wrote:
> On Fri, Feb 18, 2005 at 02:39:49PM -0800, Martin J. Bligh wrote:
> 
>>>there's something I don't understand:  With IRQBALANCE *enabled* almost
>>>all interrupts are processed on CPU0.  This changed in an unexpected way
>>>after disabling IRQBALANCE: now all interrupts are distributed uniformly
>>>to both CPUs.  Maybe it's intentional, but it's not what I expect when a
>>>config option named IRQBALANCE is *disabled*.
>>>
>>>Can anybody comment on this?
>>
>>If you have a Pentium 3 based system, by default they'll round robin.
>>If you turn on IRQbalance, they won't move until the traffic gets high
>>enough load to matter. That's presumably what you're seeing.
> 
> 
> It's an Athlon box that propably has the same behaviour.  Just another
> question on this topic:  with IRQBALANCE enabled, almost all interupts
> are routet to CPU0.  Lately irq 0 runs on CPU1 and never returns to CPU0
> - is there any obvious reason for that?

Note that it is a popular recommendation to -disable- CONFIG_IRQBALANCE, 
and then run the userspace 'irqbalanced'.

	Jeff