drm/i915: Apply rps waitboosting for dma_fence_wait_timeout()

As time goes by, usage of generic ioctls such as drm_syncobj and
sync_file are on the increase bypassing i915-specific ioctls like
GEM_WAIT. Currently, we only apply waitboosting to our driver ioctls as
we track the file/client and account the waitboosting to them. However,
since commit 7b92c1bd0540 ("drm/i915: Avoid keeping waitboost active for
signaling threads"), we no longer have been applying the client
ratelimiting on waitboosts and so that information has only been used
for debug tracking.

Push the application of waitboosting down to the common
i915_request_wait, and apply it to all foreign fence waits as well.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Eero Tamminen <eero.t.tamminen@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190213092504.25709-1-chris@chris-wilson.co.uk

1 files changed, 19 insertions, 2 deletions

diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index c2a5c48c7541..0acd6baa3c88 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -68,7 +68,9 @@ static signed long i915_fence_wait(struct dma_fence *fence,
 				   bool interruptible,
 				   signed long timeout)
 {
-	return i915_request_wait(to_request(fence), interruptible, timeout);
+	return i915_request_wait(to_request(fence),
+				 interruptible | I915_WAIT_PRIORITY,
+				 timeout);
 }
 
 static void i915_fence_release(struct dma_fence *fence)
@@ -1136,8 +1138,23 @@ long i915_request_wait(struct i915_request *rq,
 	if (__i915_spin_request(rq, state, 5))
 		goto out;
 
-	if (flags & I915_WAIT_PRIORITY)
+	/*
+	 * This client is about to stall waiting for the GPU. In many cases
+	 * this is undesirable and limits the throughput of the system, as
+	 * many clients cannot continue processing user input/output whilst
+	 * blocked. RPS autotuning may take tens of milliseconds to respond
+	 * to the GPU load and thus incurs additional latency for the client.
+	 * We can circumvent that by promoting the GPU frequency to maximum
+	 * before we sleep. This makes the GPU throttle up much more quickly
+	 * (good for benchmarks and user experience, e.g. window animations),
+	 * but at a cost of spending more power processing the workload
+	 * (bad for battery).
+	 */
+	if (flags & I915_WAIT_PRIORITY) {
+		if (!i915_request_started(rq) && INTEL_GEN(rq->i915) >= 6)
+			gen6_rps_boost(rq);
 		i915_schedule_bump_priority(rq, I915_PRIORITY_WAIT);
+	}
 
 	wait.tsk = current;
 	if (dma_fence_add_callback(&rq->fence, &wait.cb, request_wait_wake))