Hi Will, I test kernel with this patch, the problem has be fixed. When the event's sample_period is small, the cpu will not stall except printing warning "oprofile: ignoring spurious overflow ignoring spurious overflow". This is normal for unregistered event.
So would you please send a formal one? :) Thanks very much! On 2014/2/11 23:52, Will Deacon wrote: > On Tue, Feb 11, 2014 at 04:33:51AM +0000, Weng Meiling wrote: >> Hi Will, > > Hello, > >>>>> how userland can be notified about throttling. Throttling could be >>>>> worth for operf too, not only for the oprofile kernel driver. >>>>> >>> >>>>> From a quick look it seems there is also code in x86 that dynamically >>>>> adjusts the rate which might be worth being implemented for ARM too. >>>> >>>> Are you referring to the perf_sample_event_took callback? If so, that >>>> certainly looks worth persuing. I'll stick it on my list, thanks! >>>> >> >> Is there any progress on this work? Because this is important for me. >> Sorry for trouble you. > > Oops, I totally forgot about this. Does the below patch work for you? > > Will > > --->8 > > diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c > index 361a1aaee7c8..a6bc431cde70 100644 > --- a/arch/arm/kernel/perf_event.c > +++ b/arch/arm/kernel/perf_event.c > @@ -302,6 +302,8 @@ static irqreturn_t armpmu_dispatch_irq(int irq, void *dev) > struct arm_pmu *armpmu; > struct platform_device *plat_device; > struct arm_pmu_platdata *plat; > + int ret; > + u64 start_clock, finish_clock; > > if (irq_is_percpu(irq)) > dev = *(void **)dev; > @@ -309,10 +311,15 @@ static irqreturn_t armpmu_dispatch_irq(int irq, void > *dev) > plat_device = armpmu->plat_device; > plat = dev_get_platdata(&plat_device->dev); > > + start_clock = sched_clock(); > if (plat && plat->handle_irq) > - return plat->handle_irq(irq, dev, armpmu->handle_irq); > + ret = plat->handle_irq(irq, dev, armpmu->handle_irq); > else > - return armpmu->handle_irq(irq, dev); > + ret = armpmu->handle_irq(irq, dev); > + finish_clock = sched_clock(); > + > + perf_sample_event_took(finish_clock - start_clock); > + return ret; > } > > static void > diff --git a/kernel/events/core.c b/kernel/events/core.c > index 56003c6edfd3..6fcc293d77a4 100644 > --- a/kernel/events/core.c > +++ b/kernel/events/core.c > @@ -237,6 +237,8 @@ void perf_sample_event_took(u64 sample_len_ns) > u64 local_samples_len; > u64 allowed_ns = ACCESS_ONCE(perf_sample_allowed_ns); > > + pr_info("perf_sample_event_took(%llu ns)\n", sample_len_ns); > + > if (allowed_ns == 0) > return; > > > > . > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/