Re: 2.6.1 and irq balancing

[Arjan van de Ven]

On Sun, Jan 11, 2004 at 11:50:12AM -0500, Joe Korty wrote:
> On Sun, Jan 11, 2004 at 10:51:22AM +0100, Arjan van de Ven wrote:
> > On Sun, 2004-01-11 at 00:14, Ethan Weinstein wrote:
> > > 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.

well irqbalanced is a userspace balancer

> Earlier APICs had a variation where the search for where each new
> interrupt was to go started with first cpu after the one that got the
> last interrupt.  If we call this 'round-robin' allocation, then today's
> technique could be described as 'first fit'.

if it's really busy it starves cpu0 ....

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