Messages in this thread | | | Date | Tue, 30 Aug 2016 18:32:25 +0100 | From | Mark Rutland <> | Subject | Re: [PATCH] arm/perf: Fix pmu percpu irq handling at hotplug. |
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Hi,
On Fri, Aug 26, 2016 at 10:48:00AM +0100, Will Deacon wrote: > On Fri, Aug 19, 2016 at 03:25:14PM +0100, Mark Rutland wrote: > > On Thu, Aug 18, 2016 at 01:24:38PM -0700, Yabin Cui wrote: > > > If the cpu pmu is using a percpu irq: > > > > > > 1. When a cpu is down, we should disable pmu irq on > > > that cpu. Otherwise, if the cpu is still down when > > > the last perf event is released, the pmu irq can't > > > be freed. Because the irq is still enabled on the > > > offlined cpu. And following perf_event_open() > > > syscalls will fail. > > > > > > 2. When a cpu is up, we should enable pmu irq on > > > that cpu. Otherwise, profiling tools can't sample > > > events on the cpu before all perf events are > > > released, because pmu irq is disabled on that cpu.
[...]
> > Rather than adding more moving parts to the IRQ manipulation logic, I'd > > rather we rework the IRQ manipulation logic to: > > > > * At probe time, request all the interrupts. If we can't, bail out and > > fail the probe. > > > > * Upon hotplug in (and at probe time), configure the affinity and > > enable the relevant interrupt(s). > > > > * Upon hotplug out, disable the relevant interrupt.
> > I'm taking a look at doing the above, but I don't yet have a patch. > > Any update on this? I'd quite like to do *something* to fix the issues > reported here.
Apologies for the delay.
I've been away from my development hardware for the last week, so I ahven't fought with this for a few days.
Given it's requiring that I practically rewrite of_pmu_irq_cfg and friends, it may be better to take Yabin's patch for the timebeing if you want a quick fix for this particular issue.
Thanks, Mark.
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