Re: 2.6.1 and irq balancing

[Pavel Machek]

Hi!

> > > Greetings all,
> > > 
> > > I upgraded my server to 2.6.1, and I'm finding I'm saddled with only 
> > > interrupting on CPU0 again. 2.6.0 does this as well. This is the 
> > > Supermicro X5DPL-iGM-O (E7501 chipset), 2 Xeons@xxxxxx HT enabled. 
> > > /proc/cpuinfo is normal as per HT, displaying 4 cpus.
> > 
> > you should run the userspace irq balance daemon:
> > http://people.redhat.com/arjanv/irqbalance/
> 
> I have long wondered what is so evil about most interrupts going to
> CPU 0 that we felt we had to have a pair of irqdaemons in 2.6.  From my
> (admittedly imperfect) experience, the APIC will route an interrupt to
> CPU 1 if CPU 0 is busy with another interrupt, to CPU 2 if 0 and 1 are
> so occupied, and so on.  I see no harm in this other than the strangely
> lopsided /proc/interrupt displays, which I can live with.

Well, imagine 8 CPU machine with high interrupt load. Poor process
that gets scheduled on CPU#0 does little progress, but is shown as
eating one whole CPU.
								Pavel
-- 
When do you have a heart between your knees?
[Johanka's followup: and *two* hearts?]
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