From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
We can use engine busy stats instead of the MMIO sampling timer
for better efficiency.
As minimum this saves period * num_engines / sec mmio reads,
and in a better case, when only engine busy samplers are active,
it enables us to not kick off the sampling timer at all.
v2: Rebase.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
---
drivers/gpu/drm/i915/i915_pmu.c | 86 ++++++++++++++++++++++++++++-----
drivers/gpu/drm/i915/intel_ringbuffer.h | 3 ++
2 files changed, 77 insertions(+), 12 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
index 0d9c0d07a432..3272ec0763bf 100644
--- a/drivers/gpu/drm/i915/i915_pmu.c
+++ b/drivers/gpu/drm/i915/i915_pmu.c
@@ -59,6 +59,11 @@ static u64 event_enabled_mask(struct perf_event *event)
return config_enabled_mask(event->attr.config);
}
+static bool supports_busy_stats(void)
+{
+ return i915.enable_execlists;
+}
+
static bool pmu_needs_timer(struct drm_i915_private *i915, bool gpu_active)
{
u64 enable = i915->pmu.enable;
@@ -69,6 +74,8 @@ static bool pmu_needs_timer(struct drm_i915_private *i915, bool gpu_active)
if (!gpu_active)
enable &= ~ENGINE_SAMPLE_MASK;
+ else if (supports_busy_stats())
+ enable &= ~BIT(I915_SAMPLE_BUSY);
return enable;
}
@@ -132,7 +139,8 @@ static void engines_sample(struct drm_i915_private *dev_priv)
if (enable & BIT(I915_SAMPLE_QUEUED))
engine->pmu.sample[I915_SAMPLE_QUEUED] += PERIOD;
- if (enable & BIT(I915_SAMPLE_BUSY)) {
+ if ((enable & BIT(I915_SAMPLE_BUSY)) &&
+ !engine->pmu.busy_stats) {
u32 val;
fw = grab_forcewake(dev_priv, fw);
@@ -349,14 +357,29 @@ static void i915_pmu_timer_cancel(struct perf_event *event)
hrtimer_cancel(&hwc->hrtimer);
}
+static bool engine_needs_busy_stats(struct intel_engine_cs *engine)
+{
+ return supports_busy_stats() &&
+ (engine->pmu.enable & BIT(I915_SAMPLE_BUSY));
+}
+
static void i915_pmu_enable(struct perf_event *event)
{
struct drm_i915_private *i915 =
container_of(event->pmu, typeof(*i915), pmu.base);
+ struct intel_engine_cs *engine = NULL;
unsigned long flags;
spin_lock_irqsave(&i915->pmu.lock, flags);
+ if (is_engine_event(event)) {
+ engine = intel_engine_lookup_user(i915,
+ engine_event_class(event),
+ engine_event_instance(event));
+ GEM_BUG_ON(!engine);
+ engine->pmu.enable |= BIT(engine_event_sample(event));
+ }
+
i915->pmu.enable |= event_enabled_mask(event);
if (pmu_needs_timer(i915, true) && !i915->pmu.timer_enabled) {
@@ -364,16 +387,11 @@ static void i915_pmu_enable(struct perf_event *event)
ns_to_ktime(PERIOD), 0,
HRTIMER_MODE_REL_PINNED);
i915->pmu.timer_enabled = true;
- }
-
- if (is_engine_event(event)) {
- struct intel_engine_cs *engine;
-
- engine = intel_engine_lookup_user(i915,
- engine_event_class(event),
- engine_event_instance(event));
- GEM_BUG_ON(!engine);
- engine->pmu.enable |= BIT(engine_event_sample(event));
+ } else if (is_engine_event(event) && engine_needs_busy_stats(engine) &&
+ !engine->pmu.busy_stats) {
+ engine->pmu.busy_stats = true;
+ if (!cancel_delayed_work(&engine->pmu.disable_busy_stats))
+ queue_work(i915->wq, &engine->pmu.enable_busy_stats);
}
spin_unlock_irqrestore(&i915->pmu.lock, flags);
@@ -399,10 +417,17 @@ static void i915_pmu_disable(struct perf_event *event)
engine_event_instance(event));
GEM_BUG_ON(!engine);
engine->pmu.enable &= ~BIT(engine_event_sample(event));
+ if (engine->pmu.busy_stats &&
+ !engine_needs_busy_stats(engine)) {
+ engine->pmu.busy_stats = false;
+ queue_delayed_work(i915->wq,
+ &engine->pmu.disable_busy_stats,
+ round_jiffies_up_relative(2 * HZ));
+ }
mask = 0;
for_each_engine(engine, i915, id)
mask |= engine->pmu.enable;
- mask = ~mask;
+ mask = (~mask) & ENGINE_SAMPLE_MASK;
} else {
mask = event_enabled_mask(event);
}
@@ -474,6 +499,9 @@ static void i915_pmu_event_read(struct perf_event *event)
if (WARN_ON_ONCE(!engine)) {
/* Do nothing */
+ } else if (sample == I915_SAMPLE_BUSY &&
+ engine->pmu.busy_stats) {
+ val = ktime_to_ns(intel_engine_get_busy_time(engine));
} else {
val = engine->pmu.sample[sample];
}
@@ -634,8 +662,27 @@ static const struct attribute_group *i915_pmu_attr_groups[] = {
NULL
};
+static void __enable_busy_stats(struct work_struct *work)
+{
+ struct intel_engine_cs *engine =
+ container_of(work, typeof(*engine), pmu.enable_busy_stats);
+
+ WARN_ON_ONCE(intel_enable_engine_stats(engine));
+}
+
+static void __disable_busy_stats(struct work_struct *work)
+{
+ struct intel_engine_cs *engine =
+ container_of(work, typeof(*engine), pmu.disable_busy_stats.work);
+
+ intel_disable_engine_stats(engine);
+}
+
void i915_pmu_register(struct drm_i915_private *i915)
{
+ struct intel_engine_cs *engine;
+ enum intel_engine_id id;
+
if (INTEL_GEN(i915) <= 2)
return;
@@ -651,6 +698,13 @@ void i915_pmu_register(struct drm_i915_private *i915)
spin_lock_init(&i915->pmu.lock);
hrtimer_init(&i915->pmu.timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+
+ for_each_engine(engine, i915, id) {
+ INIT_WORK(&engine->pmu.enable_busy_stats, __enable_busy_stats);
+ INIT_DELAYED_WORK(&engine->pmu.disable_busy_stats,
+ __disable_busy_stats);
+ }
+
i915->pmu.timer.function = i915_sample;
i915->pmu.enable = 0;
@@ -660,6 +714,9 @@ void i915_pmu_register(struct drm_i915_private *i915)
void i915_pmu_unregister(struct drm_i915_private *i915)
{
+ struct intel_engine_cs *engine;
+ enum intel_engine_id id;
+
if (!i915->pmu.base.event_init)
return;
@@ -669,4 +726,9 @@ void i915_pmu_unregister(struct drm_i915_private *i915)
i915->pmu.base.event_init = NULL;
hrtimer_cancel(&i915->pmu.timer);
+
+ for_each_engine(engine, i915, id) {
+ flush_work(&engine->pmu.enable_busy_stats);
+ flush_delayed_work(&engine->pmu.disable_busy_stats);
+ }
}
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 68f50ec72be6..fd5d838ca7b5 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -248,6 +248,9 @@ struct intel_engine_cs {
struct {
u32 enable;
u64 sample[4];
+ bool busy_stats;
+ struct work_struct enable_busy_stats;
+ struct delayed_work disable_busy_stats;
} pmu;
/*
--
2.9.4
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