Commit 426d0073 authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915/gt: Always enable busy-stats for execlists 



In the near future, we will utilize the busy-stats on each engine to
approximate the C0 cycles of each, and use that as an input to a manual
RPS mechanism. That entails having busy-stats always enabled and so we
can remove the enable/disable routines and simplify the pmu setup. As a
consequence of always having the stats enabled, we can also show the
current active time via sysfs/engine/xcs/active_time_ns.

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: default avatarTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200429205446.3259-1-chris@chris-wilson.co.uk
parent be1cb55a

drivers/gpu/drm/i915/gt/intel_engine.h

+0 −3
Original line number Diff line number Diff line
@@ -310,9 +310,6 @@ void intel_engine_dump(struct intel_engine_cs *engine, 
		       struct drm_printer *m,

		       const char *header, ...);



int intel_enable_engine_stats(struct intel_engine_cs *engine);

void intel_disable_engine_stats(struct intel_engine_cs *engine);



ktime_t intel_engine_get_busy_time(struct intel_engine_cs *engine);



struct i915_request *

drivers/gpu/drm/i915/gt/intel_engine_cs.c

+1 −75
Original line number Diff line number Diff line
@@ -1589,58 +1589,6 @@ void intel_engine_dump(struct intel_engine_cs *engine, 
	intel_engine_print_breadcrumbs(engine, m);

}



/**

 * intel_enable_engine_stats() - Enable engine busy tracking on engine

 * @engine: engine to enable stats collection

 *

 * Start collecting the engine busyness data for @engine.

 *

 * Returns 0 on success or a negative error code.

 */

int intel_enable_engine_stats(struct intel_engine_cs *engine)

{

	struct intel_engine_execlists *execlists = &engine->execlists;

	unsigned long flags;

	int err = 0;



	if (!intel_engine_supports_stats(engine))

		return -ENODEV;



	execlists_active_lock_bh(execlists);

	write_seqlock_irqsave(&engine->stats.lock, flags);



	if (unlikely(engine->stats.enabled == ~0)) {

		err = -EBUSY;

		goto unlock;

	}



	if (engine->stats.enabled++ == 0) {

		struct i915_request * const *port;

		struct i915_request *rq;



		engine->stats.enabled_at = ktime_get();



		/* XXX submission method oblivious? */

		for (port = execlists->active; (rq = *port); port++)

			engine->stats.active++;



		for (port = execlists->pending; (rq = *port); port++) {

			/* Exclude any contexts already counted in active */

			if (!intel_context_inflight_count(rq->context))

				engine->stats.active++;

		}



		if (engine->stats.active)

			engine->stats.start = engine->stats.enabled_at;

	}



unlock:

	write_sequnlock_irqrestore(&engine->stats.lock, flags);

	execlists_active_unlock_bh(execlists);



	return err;

}



static ktime_t __intel_engine_get_busy_time(struct intel_engine_cs *engine)

{

	ktime_t total = engine->stats.total;
@@ -1649,7 +1597,7 @@ static ktime_t __intel_engine_get_busy_time(struct intel_engine_cs *engine) 
	 * If the engine is executing something at the moment

	 * add it to the total.

	 */

	if (engine->stats.active)

	if (atomic_read(&engine->stats.active))

		total = ktime_add(total,

				  ktime_sub(ktime_get(), engine->stats.start));
@@ -1675,28 +1623,6 @@ ktime_t intel_engine_get_busy_time(struct intel_engine_cs *engine) 
	return total;

}



/**

 * intel_disable_engine_stats() - Disable engine busy tracking on engine

 * @engine: engine to disable stats collection

 *

 * Stops collecting the engine busyness data for @engine.

 */

void intel_disable_engine_stats(struct intel_engine_cs *engine)

{

	unsigned long flags;



	if (!intel_engine_supports_stats(engine))

		return;



	write_seqlock_irqsave(&engine->stats.lock, flags);

	WARN_ON_ONCE(engine->stats.enabled == 0);

	if (--engine->stats.enabled == 0) {

		engine->stats.total = __intel_engine_get_busy_time(engine);

		engine->stats.active = 0;

	}

	write_sequnlock_irqrestore(&engine->stats.lock, flags);

}



static bool match_ring(struct i915_request *rq)

{

	u32 ring = ENGINE_READ(rq->engine, RING_START);

drivers/gpu/drm/i915/gt/intel_engine_types.h

+12 −17
Original line number Diff line number Diff line
@@ -531,28 +531,16 @@ struct intel_engine_cs { 
	u32 (*get_cmd_length_mask)(u32 cmd_header);



	struct {

		/**

		 * @lock: Lock protecting the below fields.

		 */

		seqlock_t lock;

		/**

		 * @enabled: Reference count indicating number of listeners.

		 */

		unsigned int enabled;

		/**

		 * @active: Number of contexts currently scheduled in.

		 */

		unsigned int active;

		/**

		 * @enabled_at: Timestamp when busy stats were enabled.

		 */

		ktime_t enabled_at;

		atomic_t active;



		/**

		 * @start: Timestamp of the last idle to active transition.

		 *

		 * Idle is defined as active == 0, active is active > 0.

		 * @lock: Lock protecting the below fields.

		 */

		ktime_t start;

		seqlock_t lock;



		/**

		 * @total: Total time this engine was busy.

		 *
@@ -560,6 +548,13 @@ struct intel_engine_cs { 
		 * where engine is currently busy (active > 0).

		 */

		ktime_t total;



		/**

		 * @start: Timestamp of the last idle to active transition.

		 *

		 * Idle is defined as active == 0, active is active > 0.

		 */

		ktime_t start;

	} stats;



	struct {

drivers/gpu/drm/i915/gt/intel_lrc.c

+11 −33
Original line number Diff line number Diff line
@@ -1199,17 +1199,14 @@ static void intel_engine_context_in(struct intel_engine_cs *engine) 
{

	unsigned long flags;



	if (READ_ONCE(engine->stats.enabled) == 0)

	if (atomic_add_unless(&engine->stats.active, 1, 0))

		return;



	write_seqlock_irqsave(&engine->stats.lock, flags);



	if (engine->stats.enabled > 0) {

		if (engine->stats.active++ == 0)

	if (!atomic_add_unless(&engine->stats.active, 1, 0)) {

		engine->stats.start = ktime_get();

		GEM_BUG_ON(engine->stats.active == 0);

		atomic_inc(&engine->stats.active);

	}



	write_sequnlock_irqrestore(&engine->stats.lock, flags);

}
@@ -1217,36 +1214,17 @@ static void intel_engine_context_out(struct intel_engine_cs *engine) 
{

	unsigned long flags;



	if (READ_ONCE(engine->stats.enabled) == 0)

	GEM_BUG_ON(!atomic_read(&engine->stats.active));



	if (atomic_add_unless(&engine->stats.active, -1, 1))

		return;



	write_seqlock_irqsave(&engine->stats.lock, flags);



	if (engine->stats.enabled > 0) {

		ktime_t last;



		if (engine->stats.active && --engine->stats.active == 0) {

			/*

			 * Decrement the active context count and in case GPU

			 * is now idle add up to the running total.

			 */

			last = ktime_sub(ktime_get(), engine->stats.start);



			engine->stats.total = ktime_add(engine->stats.total,

							last);

		} else if (engine->stats.active == 0) {

			/*

			 * After turning on engine stats, context out might be

			 * the first event in which case we account from the

			 * time stats gathering was turned on.

			 */

			last = ktime_sub(ktime_get(), engine->stats.enabled_at);



			engine->stats.total = ktime_add(engine->stats.total,

							last);

		}

	if (atomic_dec_and_test(&engine->stats.active)) {

		engine->stats.total =

			ktime_add(engine->stats.total,

				  ktime_sub(ktime_get(), engine->stats.start));

	}



	write_sequnlock_irqrestore(&engine->stats.lock, flags);

}

drivers/gpu/drm/i915/i915_pmu.c

+1 −31
Original line number Diff line number Diff line
@@ -439,29 +439,9 @@ static u64 count_interrupts(struct drm_i915_private *i915) 
	return sum;

}



static void engine_event_destroy(struct perf_event *event)

{

	struct drm_i915_private *i915 =

		container_of(event->pmu, typeof(*i915), pmu.base);

	struct intel_engine_cs *engine;



	engine = intel_engine_lookup_user(i915,

					  engine_event_class(event),

					  engine_event_instance(event));

	if (drm_WARN_ON_ONCE(&i915->drm, !engine))

		return;



	if (engine_event_sample(event) == I915_SAMPLE_BUSY &&

	    intel_engine_supports_stats(engine))

		intel_disable_engine_stats(engine);

}



static void i915_pmu_event_destroy(struct perf_event *event)

{

	WARN_ON(event->parent);



	if (is_engine_event(event))

		engine_event_destroy(event);

}



static int
@@ -514,23 +494,13 @@ static int engine_event_init(struct perf_event *event) 
	struct drm_i915_private *i915 =

		container_of(event->pmu, typeof(*i915), pmu.base);

	struct intel_engine_cs *engine;

	u8 sample;

	int ret;



	engine = intel_engine_lookup_user(i915, engine_event_class(event),

					  engine_event_instance(event));

	if (!engine)

		return -ENODEV;



	sample = engine_event_sample(event);

	ret = engine_event_status(engine, sample);

	if (ret)

		return ret;



	if (sample == I915_SAMPLE_BUSY && intel_engine_supports_stats(engine))

		ret = intel_enable_engine_stats(engine);



	return ret;

	return engine_event_status(engine, engine_event_sample(event));

}



static int i915_pmu_event_init(struct perf_event *event)

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