Start irqbalance by default

Martin Pitt martin.pitt at
Mon Jan 11 13:01:50 GMT 2010

Hello all,

Reinhard, Matt, Soren, thanks for the heads-up. Sounds a lot less like
voodoo to me now.

Reinhard Tartler [2010-01-11 12:32 +0100]:
> I assume (but this may be wrong) that the kernel default is to route all
> irqs to the primary boot CPU. This is actually not a bad choice at all
> IMO, this leaves the other CPUs unoccupied with handling hardware
> request, which means that they are free to do other tasks like userspace
> applications.

... or not wake up at all to conserve power.

> Here at work we use 2 thin client servers (debian/lenny though) where we
> have experimented with irqbalance as well. The result was that
> experienced packet loss on the network card. This is certainly a bug in
> the network driver that should be fixed, but you see, changing the
> kernel interrupt handling model can and does have very subtle
> consequences on the whole system.

Thanks for sharing. It might be interesting to enable it on many lucid
systems and collect some experience how it behaves, affects battery
lifetime, and regressions that it causes. It might not be appropriate
to enable this in an LTS, but if the server team wants to support it,
we could put it into main and announce it in the release notes at

Martin Pitt                        |
Ubuntu Developer (  | Debian Developer  (

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