On 2023-06-02 08:04, Ilkka Koskinen wrote:
Hi Robin,
On Thu, 1 Jun 2023, Robin Murphy wrote:
On 2023-06-01 04:01, Ilkka Koskinen wrote:
Some of the PMUs may share the interrupt. Support them by
setting IRQF_SHARED
This has the usual problem of allowing any PMU instance to move the
IRQ affinity to a different CPU without also migrating all the other
PMU contexts, and thus breaking perf core's assumptions of mutual
exclusion.
I see, I wasn't aware of such an assumption. Sounds like there isn't
necessarily an easy and clean solution for the shared interrupt case. I
drop the patch and get back on the issue if we come up with something
reasonable later.
What comes to mind is factoring out the explicit interrupt-sharing
machinery that we wrote to solve this problem in arm_dmc620_pmu, or
possibly trying to do something with IRQ affinity notifiers (however, I
recall looking into that a while ago and it didn't seem like they
actually interact with CPU hotplug in the way we'd want).
Thanks,
Robin.
