Re: Although CONFIG_IRQBALANCE is enabled IRQ's don't seem to be balanced very well

[Jesper Juhl]

On 1/10/06, Martin Bligh <mbligh@xxxxxxxxxx> wrote:
> Jesper Juhl wrote:
> > On 1/10/06, Martin Bligh <mbligh@xxxxxxxxxx> wrote:
> >
> >>Josef Sipek wrote:
> >>
> >>>On Tue, Jan 10, 2006 at 12:14:42PM +0100, Jesper Juhl wrote:
> >>>
> >>>
> >>>>Do I need any userspace tools in addition to CONFIG_IRQBALANCE?
> >>>
> >>>
> >>>Last I checked, yes you do need "irqbalance" (at least that's what
> >>>the package is called in debian.
> >>
> >>Nope - you need the kernel option turned on OR the userspace daemon,
> >>not both.
> >>
> >
> > Ok, good to know.
> >
> >
> >>If you're not generating interrupts at a high enough rate, it won't
> >>rotate. That's deliberate.
> >>
> >
> >
> > Hmm, and what would count as "a high enough rate"?
> >
> > I just did a small test with thousands of  ping -f's through my NIC
> > while at the same time giving the disk a good workout with tons of
> > find's, sync's & updatedb's - that sure did drive up the number of
> > interrupts and my load average went sky high (amazingly the box was
> > still fairly responsive):
> >
> > root@dragon:/home/juhl# uptime
> >  22:59:58 up 12:43,  1 user,  load average: 1015.48, 715.93, 429.07
> >
> > but, not a single interrupt was handled by CPU1, they all went to CPU0.
> >
> > Do you have a good way to drive up the nr of interrupts above the
> > treshhold for balancing?
>
> Is it HT? ISTR it was intelligent enough to ignore that. But you'd
> have to look at the code to be sure.
>
Dual Core Athlon 64 X2 4400+

--
Jesper Juhl <jesper.juhl@xxxxxxxxx>
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