Bug#696059: linux: PATCH required for server interrupt load balancing/irqbalance (tested)
On Sun, 16 Dec 2012, Ben Hutchings wrote:
> On Sun, 2012-12-16 at 11:24 -0200, Henrique de Moraes Holschuh wrote:
> > Package: linux
> > Version: 3.2.35-1
> > Severity: important
> > Tags: patch
> >
> > Please include the attached patch in Wheezy, without it, irqbalance fails to
> > do its job properly on any server (actually any multi-core system with
> > MSI/MSI-X irqs).
> >
> > It is important to have irqbalance work properly out-of-the-box, since it is
> > the only trivial way to get better network/storage behaviour out of the
> > MSI-X capable NUMA systems that are >95% of the post-2010 server market.
>
> Would be nice, but it has been broken for so long that 'everyone knows'
> to disable irqbalance.
Yeah, and nobody knows how to use hwloc either, so they probably leave it at
whatever the kernel/BIOS/EFI default mapping is. And since the kernel
doesn't irqbalance by itself anymore, it will either be round-robin if
you're lucky, or all-in-the-first-core if you're unlucky...
> > I've tested the attached patch on stock (kernel.org) 3.2.34 on production,
> > and it works fine. The patch is very simple, it just publishes the MSI
> > IRQ vector information to sysfs, which irqbalance uses.
>
> Changes ABI, so will have to wait if we apply it at all.
It is a new ABI, actually, so it has no ill effects on existing
applications. And this new ABI is already stable, too.
> > git commit upstream: b50cac55bf859d5b2fdcc1803a553a251b703456
> >
> > Alternatively, we might want to add it to -stable series upstream, on the
> > grounds that it is widely desired functionality (i.e. useful for all
> > distros).
>
> This doesn't suddenly become urgent because you just noticed it.
I don't recall claiming for urgency anywhere, unless you mean the request
that it should be added to the Wheezy kernel.
--
"One disk to rule them all, One disk to find them. One disk to bring
them all and in the darkness grind them. In the Land of Redmond
where the shadows lie." -- The Silicon Valley Tarot
Henrique Holschuh
Reply to: