Re: [RFC 0/4] dynamically allocate arch specific system vectors

H. Peter Anvin
2008-09-18T01:14:24Z

Eric W. Biederman wrote:
>> It is one vector for each cpu.
>>
>> It is more efficient for software if the vector # is the same for all cpus
> Why? Especially in terms of irq counting that would seem to lead to cache
> line conflicts.
>
>> but the software/hardware can support a unique vector for each cpu. This
>> assumes, of course, that the driver can determine the irq->vector mapping for
>> each cpu.
>
> That sounds like you have a non-standard MSI-X vector. You certainly have all of
> the same properties. At which point create_irq() sounds like what you want.
>
> One irq per cpu, per device.
>
> It is the trend. Don't worry all of the high performance drivers are doing it.
> That is the path that will be optimized.
>

In particular, it's just another interrupt type. We already have quite
a few of those, from XT-PIC to the various IOAPIC ones, to MSI and MSI-X.

Just treating these as variants of MSI seems to me to make most sense, too.

-hpa