[PATCH 14/15] nosemacb

[Chris Wilson]

---
 drivers/gpu/drm/i915/i915_request.c | 50 ++---------------------------
 drivers/gpu/drm/i915/i915_request.h |  1 -
 2 files changed, 2 insertions(+), 49 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index 8f14cc88475e..413f97302d43 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -120,7 +120,6 @@ static void i915_fence_release(struct dma_fence *fence)
 	 * caught trying to reuse dead objects.
 	 */
 	i915_sw_fence_fini(&rq->submit);
-	i915_sw_fence_fini(&rq->semaphore);
 
 	/* Keep one request on each engine for reserved use under mempressure */
 	if (!cmpxchg(&rq->engine->request_pool, NULL, rq))
@@ -451,26 +450,6 @@ bool __i915_request_submit(struct i915_request *request)
 	if (unlikely(fatal_error(request->fence.error)))
 		__i915_request_skip(request);
 
-	/*
-	 * Are we using semaphores when the gpu is already saturated?
-	 *
-	 * Using semaphores incurs a cost in having the GPU poll a
-	 * memory location, busywaiting for it to change. The continual
-	 * memory reads can have a noticeable impact on the rest of the
-	 * system with the extra bus traffic, stalling the cpu as it too
-	 * tries to access memory across the bus (perf stat -e bus-cycles).
-	 *
-	 * If we installed a semaphore on this request and we only submit
-	 * the request after the signaler completed, that indicates the
-	 * system is overloaded and using semaphores at this time only
-	 * increases the amount of work we are doing. If so, we disable
-	 * further use of semaphores until we are idle again, whence we
-	 * optimistically try again.
-	 */
-	if (request->sched.semaphores &&
-	    i915_sw_fence_signaled(&request->semaphore))
-		request->context->saturated |= request->sched.semaphores;
-
 	engine->emit_fini_breadcrumb(request,
 				     request->ring->vaddr + request->postfix);
 
@@ -536,10 +515,6 @@ void __i915_request_unsubmit(struct i915_request *request)
 
 	spin_unlock(&request->lock);
 
-	/* We've already spun, don't charge on resubmitting. */
-	if (request->sched.semaphores && i915_request_started(request))
-		request->sched.semaphores = 0;
-
 	/*
 	 * We don't need to wake_up any waiters on request->execute, they
 	 * will get woken by any other event or us re-adding this request
@@ -596,23 +571,6 @@ submit_notify(struct i915_sw_fence *fence, enum i915_sw_fence_notify state)
 	return NOTIFY_DONE;
 }
 
-static int __i915_sw_fence_call
-semaphore_notify(struct i915_sw_fence *fence, enum i915_sw_fence_notify state)
-{
-	struct i915_request *rq = container_of(fence, typeof(*rq), semaphore);
-
-	switch (state) {
-	case FENCE_COMPLETE:
-		break;
-
-	case FENCE_FREE:
-		i915_request_put(rq);
-		break;
-	}
-
-	return NOTIFY_DONE;
-}
-
 static void retire_requests(struct intel_timeline *tl)
 {
 	struct i915_request *rq, *rn;
@@ -668,7 +626,6 @@ static void __i915_request_ctor(void *arg)
 	spin_lock_init(&rq->lock);
 	i915_sched_node_init(&rq->sched);
 	i915_sw_fence_init(&rq->submit, submit_notify);
-	i915_sw_fence_init(&rq->semaphore, semaphore_notify);
 
 	dma_fence_init(&rq->fence, &i915_fence_ops, &rq->lock, 0, 0);
 
@@ -757,7 +714,6 @@ __i915_request_create(struct intel_context *ce, gfp_t gfp)
 
 	/* We bump the ref for the fence chain */
 	i915_sw_fence_reinit(&i915_request_get(rq)->submit);
-	i915_sw_fence_reinit(&i915_request_get(rq)->semaphore);
 
 	i915_sched_node_reinit(&rq->sched);
 
@@ -981,7 +937,6 @@ emit_semaphore_wait(struct i915_request *to,
 		    gfp_t gfp)
 {
 	const intel_engine_mask_t mask = READ_ONCE(from->engine)->mask;
-	struct i915_sw_fence *wait = &to->submit;
 
 	if (!intel_context_use_semaphores(to->context))
 		goto await_fence;
@@ -1016,10 +971,10 @@ emit_semaphore_wait(struct i915_request *to,
 		goto await_fence;
 
 	to->sched.semaphores |= mask;
-	wait = &to->semaphore;
+	return 0;
 
 await_fence:
-	return i915_sw_fence_await_dma_fence(wait,
+	return i915_sw_fence_await_dma_fence(&to->submit,
 					     &from->fence, 0,
 					     I915_FENCE_GFP);
 }
@@ -1637,7 +1592,6 @@ void __i915_request_queue(struct i915_request *rq,
 	 */
 	if (attr && rq->engine->schedule)
 		rq->engine->schedule(rq, attr);
-	i915_sw_fence_commit(&rq->semaphore);
 	i915_sw_fence_commit(&rq->submit);
 }
 
diff --git a/drivers/gpu/drm/i915/i915_request.h b/drivers/gpu/drm/i915/i915_request.h
index 8ec7ee4dbadc..246c80dd37f1 100644
--- a/drivers/gpu/drm/i915/i915_request.h
+++ b/drivers/gpu/drm/i915/i915_request.h
@@ -215,7 +215,6 @@ struct i915_request {
 		} duration;
 	};
 	struct list_head execute_cb;
-	struct i915_sw_fence semaphore;
 
 	/*
 	 * A list of everyone we wait upon, and everyone who waits upon us.
-- 
2.20.1