[PATCH V4 2/2] arm64: perf: add support for percpu pmu interrupt
Vinayak Kale
vkale at apm.com
Wed Nov 20 12:28:50 EST 2013
Hi Marc,
On Wed, Nov 20, 2013 at 6:44 PM, Marc Zyngier <marc.zyngier at arm.com> wrote:
> [dropped patches at apm.com]
>
> Vinayak,
>
> Please keep reviewers on CC, as it makes easier to track the changes.
Sure, will do.
>
> On 20/11/13 11:13, Vinayak Kale wrote:
>> Add support for irq registration when pmu interrupt is percpu.
>>
>> Signed-off-by: Vinayak Kale <vkale at apm.com>
>> Signed-off-by: Tuan Phan <tphan at apm.com>
>> ---
>> arch/arm64/kernel/perf_event.c | 108 ++++++++++++++++++++++++++++++----------
>> 1 file changed, 81 insertions(+), 27 deletions(-)
>>
>> diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c
>> index cea1594..de12ba8 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 +364,55 @@ 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());
>> + if (irqs < 1)
>> + return;
>>
>> - 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);
>> + irq = platform_get_irq(pmu_device, 0);
>> + if (irq < 0)
>
> So I'm going to sound like a stuck record: irq == 0 is not a valid IRQ
> number, full stop. This is how we express the fact that there is no IRQ.
>
> If you're touching that code, you might as well fix this buglet.
In Will's existing code, I think he was taking care of 'no IRQ' case
by comparing pmu_device->num_resources. Do you think this is not
enough and we must enforce the check after each platform_get_irq()?
Existing driver code snippet as below for quick reference.
[snip]
static int
armpmu_reserve_hardware(struct arm_pmu *armpmu)
{
int i, err, irq, irqs;
struct platform_device *pmu_device = armpmu->plat_device;
if (!pmu_device) {
pr_err("no PMU device registered\n");
return -ENODEV;
}
irqs = min(pmu_device->num_resources, num_possible_cpus());
if (irqs < 1) {
pr_err("no irqs for PMUs defined\n");
return -ENODEV;
}
for (i = 0; i < irqs; ++i) {
err = 0;
irq = platform_get_irq(pmu_device, i);
if (irq < 0)
continue;
[snip]
>
>> + return;
>> +
>> + if (irq_is_percpu(irq)) {
>> + on_each_cpu(armpmu_disable_percpu_irq, armpmu, 1);
>> + free_percpu_irq(irq, &cpu_hw_events);
>> + } else {
>> + 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)
>
> Same here.
>
>> + 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 +430,54 @@ 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 (irq < 0) {
>
> And here.
>
>> + pr_err("failed to get an irq for PMU device\n");
>> + return -ENODEV;
>> + }
>>
>> - /*
>> - * 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)
>
> And here.
>
>> + 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;
>>
>
> M.
> --
> Jazz is not dead. It just smells funny...
>
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