[RFC 07/17] drm/i915/pmu: Add interrupt count metric

Tvrtko Ursulin
2017-10-25T15:36:48Z

For clients like intel-gpu-overlay it is easier to read the
count via the perf API than having to parse /proc.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
---
drivers/gpu/drm/i915/i915_pmu.c | 23 +++++++++++++++++++++++
include/uapi/drm/i915_drm.h | 4 +++-
2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
index 0f6aa0337bab..2e049205eb59 100644
--- a/drivers/gpu/drm/i915/i915_pmu.c
+++ b/drivers/gpu/drm/i915/i915_pmu.c
@@ -277,6 +277,22 @@ static enum hrtimer_restart i915_sample(struct hrtimer *hrtimer)
return HRTIMER_RESTART;
}

+static u64 count_interrupts(struct drm_i915_private *i915)
+{
+ /* open-coded kstat_irqs() */
+ struct irq_desc *desc = irq_to_desc(i915->drm.pdev->irq);
+ u64 sum = 0;
+ int cpu;
+
+ if (!desc || !desc->kstat_irqs)
+ return 0;
+
+ for_each_possible_cpu(cpu)
+ sum += *per_cpu_ptr(desc->kstat_irqs, cpu);
+
+ return sum;
+}
+
static void i915_pmu_event_destroy(struct perf_event *event)
{
WARN_ON(event->parent);
@@ -343,6 +359,8 @@ static int i915_pmu_event_init(struct perf_event *event)
if (INTEL_GEN(i915) < 6)
ret = -ENODEV;
break;
+ case I915_PMU_INTERRUPTS:
+ break;
default:
ret = -ENOENT;
break;
@@ -392,6 +410,9 @@ static u64 __i915_pmu_event_read(struct perf_event *event)
div_u64(i915->pmu.sample[__I915_SAMPLE_FREQ_REQ].cur,
FREQUENCY);
break;
+ case I915_PMU_INTERRUPTS:
+ val = count_interrupts(i915);
+ break;
}
}

@@ -654,6 +675,8 @@ static struct attribute *i915_pmu_events_attrs[] = {
I915_EVENT(actual-frequency, I915_PMU_ACTUAL_FREQUENCY, "MHz"),
I915_EVENT(requested-frequency, I915_PMU_REQUESTED_FREQUENCY, "MHz"),

+ I915_EVENT_ATTR(interrupts, I915_PMU_INTERRUPTS),
+
NULL,
};

diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index d35af9ff635c..8aceb7f57e0c 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -132,7 +132,9 @@ enum drm_i915_pmu_engine_sample {
#define I915_PMU_ACTUAL_FREQUENCY __I915_PMU_OTHER(0)
#define I915_PMU_REQUESTED_FREQUENCY __I915_PMU_OTHER(1)

-#define I915_PMU_LAST I915_PMU_REQUESTED_FREQUENCY
+#define I915_PMU_INTERRUPTS __I915_PMU_OTHER(2)
+
+#define I915_PMU_LAST I915_PMU_INTERRUPTS

/* Each region is a minimum of 16k, and there are at most 255 of them.
*/