Per core, per device interrupt counts

[Andrew Brampton]

After reading though the kernel source I realise what I want isn't
implemented at the moment but I wanted to discuss if this feature
would be an useful addition.

Basically I want to see counts of how many interrupts for a particular
interrupt have fired on each core. Linux has provided this kind of
information for a while and I've found it quite useful. I would like
this information when I am pinning particular interrupts to one (or
more cores). This is useful when I'm tweaking a system with, for
example, 10Gig network cards which have multiple queues (thus multiple
IRQs).

Having a look in the kernel I see that the count is kept in the
is_count field of the intsrc struct. This field seems to be backed by
the global intrcnt array. Could this be modified to perhaps use the
new PCPU macros, so there is a different count for each core? If I was
given a few pointers I might find time to implement this myself.

thanks
Andrew