Commit 4e5c8a99 authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915: Drop i915_request.lock requirement for intel_rps_boost() 



Since we use a flag within i915_request.flags to indicate when we have
boosted the request (so that we only apply the boost) once, this can be
used as the serialisation with i915_request_retire() to avoid having to
explicitly take the i915_request.lock which is more heavily contended.

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: default avatarMika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201231093149.19086-1-chris@chris-wilson.co.uk
parent 9c080b0f

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

+1 −1
Original line number Diff line number Diff line
@@ -578,7 +578,7 @@ static int rps_boost_show(struct seq_file *m, void *data) 
		   intel_gpu_freq(rps, rps->efficient_freq),

		   intel_gpu_freq(rps, rps->boost_freq));



	seq_printf(m, "Wait boosts: %d\n", atomic_read(&rps->boosts));

	seq_printf(m, "Wait boosts: %d\n", READ_ONCE(rps->boosts));



	if (INTEL_GEN(i915) >= 6 && intel_rps_is_active(rps)) {

		struct intel_uncore *uncore = gt->uncore;

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

+13 −12
Original line number Diff line number Diff line
@@ -862,6 +862,8 @@ void intel_rps_park(struct intel_rps *rps) 
{

	int adj;



	GEM_BUG_ON(atomic_read(&rps->num_waiters));



	if (!intel_rps_clear_active(rps))

		return;
@@ -917,28 +919,27 @@ void intel_rps_park(struct intel_rps *rps) 


void intel_rps_boost(struct i915_request *rq)

{

	if (i915_request_signaled(rq) || i915_request_has_waitboost(rq))

		return;



	/* Serializes with i915_request_retire() */

	if (!test_and_set_bit(I915_FENCE_FLAG_BOOST, &rq->fence.flags)) {

		struct intel_rps *rps = &READ_ONCE(rq->engine)->gt->rps;

	unsigned long flags;



	if (i915_request_signaled(rq) || !intel_rps_is_active(rps))

		if (atomic_fetch_inc(&rps->num_waiters))

			return;



	/* Serializes with i915_request_retire() */

	spin_lock_irqsave(&rq->lock, flags);

	if (!i915_request_has_waitboost(rq) &&

	    !dma_fence_is_signaled_locked(&rq->fence)) {

		set_bit(I915_FENCE_FLAG_BOOST, &rq->fence.flags);

		if (!intel_rps_is_active(rps))

			return;



		GT_TRACE(rps_to_gt(rps), "boost fence:%llx:%llx\n",

			 rq->fence.context, rq->fence.seqno);



		if (!atomic_fetch_inc(&rps->num_waiters) &&

		    READ_ONCE(rps->cur_freq) < rps->boost_freq)

		if (READ_ONCE(rps->cur_freq) < rps->boost_freq)

			schedule_work(&rps->work);



		atomic_inc(&rps->boosts);

		WRITE_ONCE(rps->boosts, rps->boosts + 1); /* debug only */

	}

	spin_unlock_irqrestore(&rq->lock, flags);

}



int intel_rps_set(struct intel_rps *rps, u8 val)

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

+1 −1
Original line number Diff line number Diff line
@@ -93,7 +93,7 @@ struct intel_rps { 
	} power;



	atomic_t num_waiters;

	atomic_t boosts;

	unsigned int boosts;



	/* manual wa residency calculations */

	struct intel_rps_ei ei;

drivers/gpu/drm/i915/i915_debugfs.c

+1 −1
Original line number Diff line number Diff line
@@ -1232,7 +1232,7 @@ static int i915_rps_boost_info(struct seq_file *m, void *data) 
		   intel_gpu_freq(rps, rps->efficient_freq),

		   intel_gpu_freq(rps, rps->boost_freq));



	seq_printf(m, "Wait boosts: %d\n", atomic_read(&rps->boosts));

	seq_printf(m, "Wait boosts: %d\n", READ_ONCE(rps->boosts));



	if (INTEL_GEN(dev_priv) >= 6 && intel_rps_is_active(rps)) {

		u32 rpup, rpupei;

drivers/gpu/drm/i915/i915_request.c

+1 −3
Original line number Diff line number Diff line
@@ -307,10 +307,8 @@ bool i915_request_retire(struct i915_request *rq) 
		spin_unlock_irq(&rq->lock);

	}



	if (i915_request_has_waitboost(rq)) {

		GEM_BUG_ON(!atomic_read(&rq->engine->gt->rps.num_waiters));

	if (test_and_set_bit(I915_FENCE_FLAG_BOOST, &rq->fence.flags))

		atomic_dec(&rq->engine->gt->rps.num_waiters);

	}



	/*

	 * We only loosely track inflight requests across preemption,