Quoting Rogozhkin, Dmitry V (2017-11-22 21:15:24)
> On Wed, 2017-11-22 at 12:46 +0000, Tvrtko Ursulin wrote:
> > From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
> >
> > We add a PMU counter to expose the number of requests currently submitted
> > to the GPU, plus the number of runnable requests waiting on GPU time.
> >
> > This is useful to analyze the overall load of the system.
> >
> > Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
> > ---
> > drivers/gpu/drm/i915/i915_pmu.c | 30 +++++++++++++++++++++++++-----
> > include/uapi/drm/i915_drm.h | 6 ++++++
> > 2 files changed, 31 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
> > index 112243720ff3..b2b4b32af35f 100644
> > --- a/drivers/gpu/drm/i915/i915_pmu.c
> > +++ b/drivers/gpu/drm/i915/i915_pmu.c
> > @@ -36,7 +36,8 @@
> > #define ENGINE_SAMPLE_MASK \
> > (BIT(I915_SAMPLE_BUSY) | \
> > BIT(I915_SAMPLE_WAIT) | \
> > - BIT(I915_SAMPLE_SEMA))
> > + BIT(I915_SAMPLE_SEMA) | \
> > + BIT(I915_SAMPLE_QUEUED))
> >
> > #define ENGINE_SAMPLE_BITS (1 << I915_PMU_SAMPLE_BITS)
> >
> > @@ -223,6 +224,12 @@ static void engines_sample(struct drm_i915_private *dev_priv)
> >
> > update_sample(&engine->pmu.sample[I915_SAMPLE_SEMA],
> > PERIOD, !!(val & RING_WAIT_SEMAPHORE));
> > +
> > + if (engine->pmu.enable & BIT(I915_SAMPLE_QUEUED))
> > + update_sample(&engine->pmu.sample[I915_SAMPLE_QUEUED],
> > + 1 / I915_SAMPLE_QUEUED_SCALE,
> > + engine->queued +
> > + (last_seqno - current_seqno));
> > }
> >
> > if (fw)
> > @@ -310,6 +317,10 @@ static int engine_event_init(struct perf_event *event)
> > if (INTEL_GEN(i915) < 6)
> > return -ENODEV;
> > break;
> > + case I915_SAMPLE_QUEUED:
> > + if (INTEL_GEN(i915) < 8)
> > + return -ENODEV;
> > + break;
> > default:
> > return -ENOENT;
> > }
> > @@ -399,6 +410,10 @@ static u64 __i915_pmu_event_read(struct perf_event *event)
> > } else if (sample == I915_SAMPLE_BUSY &&
> > engine->pmu.busy_stats) {
> > val = ktime_to_ns(intel_engine_get_busy_time(engine));
> > + } else if (sample == I915_SAMPLE_QUEUED) {
> > + val =
> > + div_u64(engine->pmu.sample[I915_SAMPLE_QUEUED].cur,
> > + FREQUENCY);
> > } else {
> > val = engine->pmu.sample[sample].cur;
> > }
> > @@ -679,13 +694,18 @@ static ssize_t i915_pmu_event_show(struct device *dev,
> > I915_EVENT_STR(_name.unit, _unit)
> >
> > #define I915_ENGINE_EVENT(_name, _class, _instance, _sample) \
> > - I915_EVENT_ATTR(_name, __I915_PMU_ENGINE(_class, _instance, _sample)), \
> > + I915_EVENT_ATTR(_name, __I915_PMU_ENGINE(_class, _instance, _sample))
> > +
> > +#define I915_ENGINE_EVENT_NS(_name, _class, _instance, _sample) \
> > + I915_ENGINE_EVENT(_name, _class, _instance, _sample), \
> > I915_EVENT_STR(_name.unit, "ns")
> >
> > #define I915_ENGINE_EVENTS(_name, _class, _instance) \
> > - I915_ENGINE_EVENT(_name##_instance-busy, _class, _instance, I915_SAMPLE_BUSY), \
> > - I915_ENGINE_EVENT(_name##_instance-sema, _class, _instance, I915_SAMPLE_SEMA), \
> > - I915_ENGINE_EVENT(_name##_instance-wait, _class, _instance, I915_SAMPLE_WAIT)
> > + I915_ENGINE_EVENT_NS(_name##_instance-busy, _class, _instance, I915_SAMPLE_BUSY), \
> > + I915_ENGINE_EVENT_NS(_name##_instance-sema, _class, _instance, I915_SAMPLE_SEMA), \
> > + I915_ENGINE_EVENT_NS(_name##_instance-wait, _class, _instance, I915_SAMPLE_WAIT), \
> > + I915_ENGINE_EVENT(_name##_instance-queued, _class, _instance, I915_SAMPLE_QUEUED), \
> > + I915_EVENT_STR(_name##_instance-queued.scale, __stringify(I915_SAMPLE_QUEUED_SCALE))
>
> We expose queued as an "instant" metric, i.e. that's a number of
> requests on the very moment when we query the metric, i.e. that's not an
> ever growing counter - is that right? I doubt such a metric will make
> sense for perf-stat. Can we somehow restrict it to be queried by uAPI
> only and avoid perf-stat for it?
True, I forgot that Tvrtko normalised it. We don't need to, and so allow
the user to apply their own normalisation and generate average values
for the last N seconds instead; aiui.
-Chris
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