[PATCH V2 0/2] genirq: arm64: perf: support for percpu pmu interrupt

[PATCH V2 0/2] genirq: arm64: perf: support for percpu pmu interrupt

[Vinayak Kale]

This patch series adds support to handle interrupt registration/deregistration
in arm64 pmu driver when pmu interrupt type is percpu.

Changes since V1:
* To determine whether an IRQ is percpu or not, added an accessor function in
  irqdesc.h . This approach was used by Chris Smith here[1] for similar changes
  in arm pmu driver.
* In arm64 pmu driver: Got rid of unnecessary pointer typecastings.

[1] http://lkml.indiana.edu/hypermail/linux/kernel/1207.3/02955.html

Vinayak Kale (2):
  genirq: Add an accessor for IRQ_PER_CPU flag
  arm64: perf: add support for percpu pmu interrupt

 arch/arm64/kernel/perf_event.c |  102 +++++++++++++++++++++++++++++-----------
 include/linux/irqdesc.h        |    8 ++++
 2 files changed, 82 insertions(+), 28 deletions(-)

-- 
1.7.9.5

[PATCH V2 1/2] genirq: Add an accessor for IRQ_PER_CPU flag

[Vinayak Kale]

This patch adds an accessor function for IRQ_PER_CPU flag.
The accessor function is useful to dertermine whether an IRQ is percpu or not.

Signed-off-by: Vinayak Kale <vkale@apm.com>
---
 include/linux/irqdesc.h |    8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h
index 56fb646..acd8a3f 100644
--- a/include/linux/irqdesc.h
+++ b/include/linux/irqdesc.h
@@ -152,6 +152,14 @@ static inline int irq_balancing_disabled(unsigned int irq)
 	return desc->status_use_accessors & IRQ_NO_BALANCING_MASK;
 }
 
+static inline int irq_is_percpu(unsigned int irq)
+{
+	struct irq_desc *desc;
+
+	desc = irq_to_desc(irq);
+	return (desc && (desc->status_use_accessors & IRQ_PER_CPU)) ? 1 : 0;
+}
+
 static inline void
 irq_set_lockdep_class(unsigned int irq, struct lock_class_key *class)
 {
-- 
1.7.9.5

Re: [PATCH V2 1/2] genirq: Add an accessor for IRQ_PER_CPU flag

[Marc Zyngier]

Hi Vinayak,

On 13/11/13 11:05, Vinayak Kale wrote:
> This patch adds an accessor function for IRQ_PER_CPU flag.
> The accessor function is useful to dertermine whether an IRQ is percpu or not.
> 
> Signed-off-by: Vinayak Kale <vkale@apm.com>
> ---
>  include/linux/irqdesc.h |    8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h
> index 56fb646..acd8a3f 100644
> --- a/include/linux/irqdesc.h
> +++ b/include/linux/irqdesc.h
> @@ -152,6 +152,14 @@ static inline int irq_balancing_disabled(unsigned int irq)
>  	return desc->status_use_accessors & IRQ_NO_BALANCING_MASK;
>  }
>  
> +static inline int irq_is_percpu(unsigned int irq)
> +{
> +	struct irq_desc *desc;
> +
> +	desc = irq_to_desc(irq);
> +	return (desc && (desc->status_use_accessors & IRQ_PER_CPU)) ? 1 : 0;

I don't think it is worth checking for the validity of "desc" here. All
the other accessors assume that you've not passed a stupid "irq" value.

Simply having
	return !!(desc->status_use_accessors & IRQ_PER_CPU);
should be enough.

> +}
> +
>  static inline void
>  irq_set_lockdep_class(unsigned int irq, struct lock_class_key *class)
>  {
> 

Cheers,

	M.
-- 
Jazz is not dead. It just smells funny...

Re: [PATCH V2 1/2] genirq: Add an accessor for IRQ_PER_CPU flag

[Vinayak Kale]

Hi Mark,


On Wed, Nov 13, 2013 at 7:38 PM, Marc Zyngier <marc.zyngier@arm.com> wrote:
> Hi Vinayak,
>
> On 13/11/13 11:05, Vinayak Kale wrote:
>> This patch adds an accessor function for IRQ_PER_CPU flag.
>> The accessor function is useful to dertermine whether an IRQ is percpu or not.
>>
>> Signed-off-by: Vinayak Kale <vkale@apm.com>
>> ---
>>  include/linux/irqdesc.h |    8 ++++++++
>>  1 file changed, 8 insertions(+)
>>
>> diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h
>> index 56fb646..acd8a3f 100644
>> --- a/include/linux/irqdesc.h
>> +++ b/include/linux/irqdesc.h
>> @@ -152,6 +152,14 @@ static inline int irq_balancing_disabled(unsigned int irq)
>>       return desc->status_use_accessors & IRQ_NO_BALANCING_MASK;
>>  }
>>
>> +static inline int irq_is_percpu(unsigned int irq)
>> +{
>> +     struct irq_desc *desc;
>> +
>> +     desc = irq_to_desc(irq);
>> +     return (desc && (desc->status_use_accessors & IRQ_PER_CPU)) ? 1 : 0;
>
> I don't think it is worth checking for the validity of "desc" here. All
> the other accessors assume that you've not passed a stupid "irq" value.
hmm..Okay, will remove the 'desc' validity check from here.

[PATCH V2 2/2] arm64: perf: add support for percpu pmu interrupt

[Vinayak Kale]

Add support for irq registration when pmu interrupt is percpu.

Signed-off-by: Vinayak Kale <vkale@apm.com>
Signed-off-by: Tuan Phan <tphan@apm.com>
---
 arch/arm64/kernel/perf_event.c |  102 +++++++++++++++++++++++++++++-----------
 1 file changed, 74 insertions(+), 28 deletions(-)

diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c
index cea1594..a6c01cb 100644
--- a/arch/arm64/kernel/perf_event.c
+++ b/arch/arm64/kernel/perf_event.c
@@ -22,6 +22,7 @@
 
 #include <linux/bitmap.h>
 #include <linux/interrupt.h>
+#include <linux/irq.h>
 #include <linux/kernel.h>
 #include <linux/export.h>
 #include <linux/perf_event.h>
@@ -363,22 +364,51 @@ validate_group(struct perf_event *event)
 }
 
 static void
+armpmu_disable_percpu_irq(void *data)
+{
+	struct arm_pmu *armpmu = data;
+	struct platform_device *pmu_device = armpmu->plat_device;
+	int irq = platform_get_irq(pmu_device, 0);
+
+	cpumask_test_and_clear_cpu(smp_processor_id(), &armpmu->active_irqs);
+	disable_percpu_irq(irq);
+}
+
+static void
 armpmu_release_hardware(struct arm_pmu *armpmu)
 {
 	int i, irq, irqs;
 	struct platform_device *pmu_device = armpmu->plat_device;
 
-	irqs = min(pmu_device->num_resources, num_possible_cpus());
+	irq = platform_get_irq(pmu_device, 0);
 
-	for (i = 0; i < irqs; ++i) {
-		if (!cpumask_test_and_clear_cpu(i, &armpmu->active_irqs))
-			continue;
-		irq = platform_get_irq(pmu_device, i);
-		if (irq >= 0)
-			free_irq(irq, armpmu);
+	if (irq_is_percpu(irq)) {
+		on_each_cpu(armpmu_disable_percpu_irq, armpmu, 1);
+		free_percpu_irq(irq, &cpu_hw_events);
+	} else {
+		irqs = min(pmu_device->num_resources, num_possible_cpus());
+
+		for (i = 0; i < irqs; ++i) {
+			if (!cpumask_test_and_clear_cpu(i, &armpmu->active_irqs))
+				continue;
+			irq = platform_get_irq(pmu_device, i);
+			if (irq >= 0)
+				free_irq(irq, armpmu);
+		}
 	}
 }
 
+static void
+armpmu_enable_percpu_irq(void *data)
+{
+	struct arm_pmu *armpmu = data;
+	struct platform_device *pmu_device = armpmu->plat_device;
+	int irq = platform_get_irq(pmu_device, 0);
+
+	enable_percpu_irq(irq, 0);
+	cpumask_set_cpu(smp_processor_id(), &armpmu->active_irqs);
+}
+
 static int
 armpmu_reserve_hardware(struct arm_pmu *armpmu)
 {
@@ -396,34 +426,50 @@ armpmu_reserve_hardware(struct arm_pmu *armpmu)
 		return -ENODEV;
 	}
 
-	for (i = 0; i < irqs; ++i) {
-		err = 0;
-		irq = platform_get_irq(pmu_device, i);
-		if (irq < 0)
-			continue;
+	irq = platform_get_irq(pmu_device, 0);
 
-		/*
-		 * If we have a single PMU interrupt that we can't shift,
-		 * assume that we're running on a uniprocessor machine and
-		 * continue. Otherwise, continue without this interrupt.
-		 */
-		if (irq_set_affinity(irq, cpumask_of(i)) && irqs > 1) {
-			pr_warning("unable to set irq affinity (irq=%d, cpu=%u)\n",
-				    irq, i);
-			continue;
-		}
+	if (irq_is_percpu(irq)) {
+		err = request_percpu_irq(irq, armpmu->handle_irq,
+				"arm-pmu", &cpu_hw_events);
 
-		err = request_irq(irq, armpmu->handle_irq,
-				  IRQF_NOBALANCING,
-				  "arm-pmu", armpmu);
 		if (err) {
-			pr_err("unable to request IRQ%d for ARM PMU counters\n",
-				irq);
+			pr_err("unable to request percpu IRQ%d for ARM PMU counters\n",
+					irq);
 			armpmu_release_hardware(armpmu);
 			return err;
 		}
 
-		cpumask_set_cpu(i, &armpmu->active_irqs);
+		on_each_cpu(armpmu_enable_percpu_irq, armpmu, 1);
+	} else {
+		for (i = 0; i < irqs; ++i) {
+			err = 0;
+			irq = platform_get_irq(pmu_device, i);
+			if (irq < 0)
+				continue;
+
+			/*
+			 * If we have a single PMU interrupt that we can't shift,
+			 * assume that we're running on a uniprocessor machine and
+			 * continue. Otherwise, continue without this interrupt.
+			 */
+			if (irq_set_affinity(irq, cpumask_of(i)) && irqs > 1) {
+				pr_warning("unable to set irq affinity (irq=%d, cpu=%u)\n",
+						irq, i);
+				continue;
+			}
+
+			err = request_irq(irq, armpmu->handle_irq,
+					IRQF_NOBALANCING,
+					"arm-pmu", armpmu);
+			if (err) {
+				pr_err("unable to request IRQ%d for ARM PMU counters\n",
+						irq);
+				armpmu_release_hardware(armpmu);
+				return err;
+			}
+
+			cpumask_set_cpu(i, &armpmu->active_irqs);
+		}
 	}
 
 	return 0;
-- 
1.7.9.5