drm/i915: Remove superfluous worker wakeups when RPS is already boosted

We only need to wake up the RPS worker once when initially enabling the
client boost, it remains in effect then until the last client no longer
requires the boost.

References: https://bugs.freedesktop.org/show_bug.cgi?id=102250
References: 7b92c1bd0540 ("drm/i915: Avoid keeping waitboost active for signaling threads")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Michał Winiarski <michal.winiarski@intel.com>
Reviewed-by: Michał Winiarski <michal.winiarski@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180206143137.15509-1-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/i915_gem_request.c b/drivers/gpu/drm/i915/i915_gem_request.c
index a8eb22a95b0f2aa72fee52487f42ab7672be48fe..8a35b5591e0e468e1d7818c17feece69e6f1b0ee 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_request.c
+++ b/drivers/gpu/drm/i915/i915_gem_request.c
@@ -443,12 +443,14 @@ static void i915_gem_request_retire(struct drm_i915_gem_request *request)
        engine->last_retired_context = request->ctx;
 
        spin_lock_irq(&request->lock);
-       if (request->waitboost)
-               atomic_dec(&request->i915->gt_pm.rps.num_waiters);
        if (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &request->fence.flags))
                dma_fence_signal_locked(&request->fence);
        if (test_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, &request->fence.flags))
                intel_engine_cancel_signaling(request);
+       if (request->waitboost) {
+               GEM_BUG_ON(!atomic_read(&request->i915->gt_pm.rps.num_waiters));
+               atomic_dec(&request->i915->gt_pm.rps.num_waiters);
+       }
        spin_unlock_irq(&request->lock);
 
        i915_priotree_fini(request->i915, &request->priotree);

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 41f26ab46501a69ad153e5112f96506a935c5466..b2f5e3b9ada8e253ed8d18f434d4f17fad1c3364 100644 (file)
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -6374,12 +6374,15 @@ void gen6_rps_boost(struct drm_i915_gem_request *rq,
        if (!rps->enabled)
                return;
 
+       if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &rq->fence.flags))
+               return;
+
+       /* Serializes with i915_gem_request_retire() */
        boost = false;
        spin_lock_irqsave(&rq->lock, flags);
-       if (!rq->waitboost && !i915_gem_request_completed(rq)) {
-               atomic_inc(&rps->num_waiters);
+       if (!rq->waitboost && !dma_fence_is_signaled_locked(&rq->fence)) {
+               boost = !atomic_fetch_inc(&rps->num_waiters);
                rq->waitboost = true;
-               boost = true;
        }
        spin_unlock_irqrestore(&rq->lock, flags);
        if (!boost)