[PATCHv2 1/2] ARM: perf_event: allow platform-specific interrupt handler

[will.deacon@arm.com (Will Deacon)]

Hi Rabin,

> > You'll be able to target the PMU IRQ to both CPUs and avoid the need for
> > ping-ponging the affinity. This is a bit weird though as usually you'd have
> > a PPI for a percpu interrupt so this might be better off staying inside
> > platform code and leaving the GIC code alone. I also think this approach
> > is more invasive from the perf point of view.
> >
> > Unless this approach gives markedly better profiling results than your
> > proposal, I think we should go with what you've got.
> 
> I gave this a try, along with the modifications to enable IRQ_PER_CPU
> and have the pmu code use the appropriate flags and set the affinity.
> Didn't work though; it always ends up triggering the spurious IRQ check.

Hmm, that doesn't sound right. Did you have any synchronisation to ensure
that the CPU without the overflow didn't return IRQ_NONE until the handling
CPU had returned IRQ_HANDLED?

Will