[PATCH 6/6] drm/i915/pmu: Add running counter

Tvrtko Ursulin
2018-02-12T18:57:56Z

We add a PMU counter to expose the number of requests currently executing
on the GPU.

This is useful to analyze the overall load of the system.

v2:
* Rebase.
* Drop floating point constant. (Chris Wilson)

v3:
* Change scale to 1024 for faster arithmetics. (Chris Wilson)

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
---
drivers/gpu/drm/i915/i915_pmu.c | 18 ++++++++++++++++--
drivers/gpu/drm/i915/intel_ringbuffer.h | 2 +-
include/uapi/drm/i915_drm.h | 5 +++++
3 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
index 7acf5cf96266..710ae4bfd52e 100644
--- a/drivers/gpu/drm/i915/i915_pmu.c
+++ b/drivers/gpu/drm/i915/i915_pmu.c
@@ -38,7 +38,8 @@
BIT(I915_SAMPLE_WAIT) | \
BIT(I915_SAMPLE_SEMA) | \
BIT(I915_SAMPLE_QUEUED) | \
- BIT(I915_SAMPLE_RUNNABLE))
+ BIT(I915_SAMPLE_RUNNABLE) | \
+ BIT(I915_SAMPLE_RUNNING))

#define ENGINE_SAMPLE_BITS (1 << I915_PMU_SAMPLE_BITS)

@@ -232,6 +233,11 @@ static void engines_sample(struct drm_i915_private *dev_priv)
update_sample(&engine->pmu.sample[I915_SAMPLE_RUNNABLE],
I915_SAMPLE_RUNNABLE_DIVISOR,
engine->request_stats.runnable);
+
+ if (engine->pmu.enable & BIT(I915_SAMPLE_RUNNING))
+ update_sample(&engine->pmu.sample[I915_SAMPLE_RUNNING],
+ I915_SAMPLE_RUNNING_DIVISOR,
+ last_seqno - current_seqno);
}

if (fw)
@@ -331,6 +337,7 @@ engine_event_status(struct intel_engine_cs *engine,
case I915_SAMPLE_WAIT:
case I915_SAMPLE_QUEUED:
case I915_SAMPLE_RUNNABLE:
+ case I915_SAMPLE_RUNNING:
break;
case I915_SAMPLE_SEMA:
if (INTEL_GEN(engine->i915) < 6)
@@ -540,7 +547,8 @@ static u64 __i915_pmu_event_read(struct perf_event *event, bool locked)
}

if (sample == I915_SAMPLE_QUEUED ||
- sample == I915_SAMPLE_RUNNABLE)
+ sample == I915_SAMPLE_RUNNABLE ||
+ sample == I915_SAMPLE_RUNNING)
val = div_u64(val, FREQUENCY);
} else {
switch (event->attr.config) {
@@ -837,6 +845,7 @@ add_pmu_attr(struct perf_pmu_events_attr *attr, const char *name,
/* No brackets or quotes below please. */
#define I915_SAMPLE_QUEUED_SCALE 0.0009765625
#define I915_SAMPLE_RUNNABLE_SCALE 0.0009765625
+#define I915_SAMPLE_RUNNING_SCALE 0.0009765625

static struct attribute **
create_event_attributes(struct drm_i915_private *i915)
@@ -864,6 +873,8 @@ create_event_attributes(struct drm_i915_private *i915)
__stringify(I915_SAMPLE_QUEUED_SCALE)),
__engine_event_scale(I915_SAMPLE_RUNNABLE, "runnable",
__stringify(I915_SAMPLE_RUNNABLE_SCALE)),
+ __engine_event_scale(I915_SAMPLE_RUNNING, "running",
+ __stringify(I915_SAMPLE_RUNNING_SCALE)),
};
unsigned int count = 0;
struct perf_pmu_events_attr *pmu_attr = NULL, *pmu_iter;
@@ -879,6 +890,9 @@ create_event_attributes(struct drm_i915_private *i915)
BUILD_BUG_ON(I915_SAMPLE_RUNNABLE_DIVISOR !=
(1 / I915_SAMPLE_RUNNABLE_SCALE));

+ BUILD_BUG_ON(I915_SAMPLE_RUNNING_DIVISOR !=
+ (1 / I915_SAMPLE_RUNNING_SCALE));
+
/* Count how many counters we will be exposing. */
for (i = 0; i < ARRAY_SIZE(events); i++) {
if (!config_status(i915, events[i].config))
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 3803b544fb2e..092b786b18ad 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -386,7 +386,7 @@ struct intel_engine_cs {
*
* Our internal timer stores the current counters in this field.
*/
-#define I915_ENGINE_SAMPLE_MAX (I915_SAMPLE_RUNNABLE + 1)
+#define I915_ENGINE_SAMPLE_MAX (I915_SAMPLE_RUNNING + 1)
struct i915_pmu_sample sample[I915_ENGINE_SAMPLE_MAX];
} pmu;

diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index 3e59cc009c4f..038276505e80 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -113,11 +113,13 @@ enum drm_i915_pmu_engine_sample {
I915_SAMPLE_SEMA = 2,
I915_SAMPLE_QUEUED = 3,
I915_SAMPLE_RUNNABLE = 4,
+ I915_SAMPLE_RUNNING = 5,
};

/* Divide counter value by divisor to get the real value. */
#define I915_SAMPLE_QUEUED_DIVISOR (1024)
#define I915_SAMPLE_RUNNABLE_DIVISOR (1024)
+#define I915_SAMPLE_RUNNING_DIVISOR (1024)

#define I915_PMU_SAMPLE_BITS (4)
#define I915_PMU_SAMPLE_MASK (0xf)
@@ -145,6 +147,9 @@ enum drm_i915_pmu_engine_sample {
#define I915_PMU_ENGINE_RUNNABLE(class, instance) \
__I915_PMU_ENGINE(class, instance, I915_SAMPLE_RUNNABLE)

+#define I915_PMU_ENGINE_RUNNING(class, instance) \
+ __I915_PMU_ENGINE(class, instance, I915_SAMPLE_RUNNING)
+
#define __I915_PMU_OTHER(x) (__I915_PMU_ENGINE(0xff, 0xff, 0xf) + 1 + (x))

#define I915_PMU_ACTUAL_FREQUENCY __I915_PMU_OTHER(0)