Re: [RFC PATCH] PCI: remove access to pci_[enable|disable]_msi() for drivers - take 2

Ashok Raj
2005-06-08T16:13:31Z

On Wed, Jun 08, 2005 at 06:32:26AM -0700, Andi Kleen wrote:
>
> > I also see one minor weakness in the assumption that CPU Vectors
> > are global. Both IA64/PARISC can support per-CPU Vector tables.

One thing to keep in mind is that since now we have support for CPU hotplug
we need to factor in cases when cpu is removed, the per-cpu vectors would
require migrating to a new cpu far interrupt target. Which would
possibly require vector-sharing support as well in case the vector is used
in all other cpus.

Possibly irq balancer might need to be revisited as well, and potentially
might trigger some sharing needs.

A combination of
- Not allocating IRQs to pins not used (Which Natalie from Unisys
submitted)
http://marc.theaimsgroup.com/?l=linux-kernel&m=111656957923038&w=2
- per-cpu vector tables (long back i remember seeing some post from sgi
on the topic, possibly under intr domains etc.. not too sure)
- vector sharing

>
> x86-64 will eventually too, I definitely plan for it at some point.
> We need it for very big machines where 255 interrupt vectors
> are not enough. And as you say with MSI-X it becomes even more
> important.
>
> -Andi
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--
Cheers,
Ashok Raj
- Open Source Technology Center