Re: [PATCH] pci: change msi-x vector to 32bit

Yinghai Lu
2008-08-16T22:17:45Z

On Sat, Aug 16, 2008 at 1:45 PM, James Bottomley
<James.Bottomley@hansenpartnership.com> wrote:
>> > What I still don't quite get is the benefit of large IRQ spaces ...
>> > particularly if you encode things the system doesn't really need to know
>> > in them.
>>
>> then set nr_irqs = nr_cpu_ids * NR_VECTORS))
>> and count down for msi/msi-x?
>
> No, what I mean is that msis can trip directly to CPUs, so this is an
> affinity thing (that MSI is directly bound to that CPU now), so in the
> matrixed way we display this in show_interrupts() with the CPU along the
> top and the IRQ down the side, it doesn't make sense to me to encode IRQ
> affinity in the irq number again. So it makes more sense to assign the
> vectors based on both the irq number and the CPU affinity so that if the
> PCI MSI for qla is assigned to CPU4 you can reassign it to CPU5 and so
> on.

msi-x entry index, cpu_vector, irq number...

you want to different cpus have same vector?

YH