[PATCH v4 3/7] drm/i915: Keep a count of requests submitted from userspace

[Tvrtko Ursulin <tursulin@ursulin.net>]

From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

Keep a count of requests submitted from userspace and not yet runnable due
unresolved dependencies.

v2: Rename and move under the container struct. (Chris Wilson)
v3: Rebase.
v4: Move decrement site to the backend to shrink the window of double-
    accounting as much as possible. (Chris Wilson)

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
---
 drivers/gpu/drm/i915/i915_request.c     | 3 +++
 drivers/gpu/drm/i915/intel_engine_cs.c  | 3 ++-
 drivers/gpu/drm/i915/intel_lrc.c        | 2 ++
 drivers/gpu/drm/i915/intel_ringbuffer.h | 8 ++++++++
 4 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index 2617bd008845..997be595d7e7 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -511,6 +511,7 @@ void i915_request_submit(struct i915_request *request)
 	spin_lock_irqsave(&engine->timeline->lock, flags);
 
 	engine->request_stats.runnable++;
+	atomic_dec(&engine->request_stats.queued);
 
 	__i915_request_submit(request);
 
@@ -1072,6 +1073,8 @@ void __i915_request_add(struct i915_request *request, bool flush_caches)
 		engine->schedule(request, request->ctx->priority);
 	rcu_read_unlock();
 
+	atomic_inc(&engine->request_stats.queued);
+
 	local_bh_disable();
 	i915_sw_fence_commit(&request->submit);
 	local_bh_enable(); /* Kick the execlists tasklet if just scheduled */
diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
index 98254ff92785..e4992c2e23a4 100644
--- a/drivers/gpu/drm/i915/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/intel_engine_cs.c
@@ -1934,12 +1934,13 @@ void intel_engine_dump(struct intel_engine_cs *engine,
 	if (i915_terminally_wedged(&engine->i915->gpu_error))
 		drm_printf(m, "*** WEDGED ***\n");
 
-	drm_printf(m, "\tcurrent seqno %x, last %x, hangcheck %x [%d ms], inflight %d, runnable %u\n",
+	drm_printf(m, "\tcurrent seqno %x, last %x, hangcheck %x [%d ms], inflight %d, queued %u, runnable %u\n",
 		   intel_engine_get_seqno(engine),
 		   intel_engine_last_submit(engine),
 		   engine->hangcheck.seqno,
 		   jiffies_to_msecs(jiffies - engine->hangcheck.action_timestamp),
 		   engine->timeline->inflight_seqnos,
+		   atomic_read(&engine->request_stats.queued),
 		   engine->request_stats.runnable);
 	drm_printf(m, "\tReset count: %d (global %d)\n",
 		   i915_reset_engine_count(error, engine),
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 16ea95ff7c51..ddd14e30be6c 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -1124,7 +1124,9 @@ static void execlists_submit_request(struct i915_request *request)
 
 	queue_request(engine, &request->priotree, rq_prio(request));
 	submit_queue(engine, rq_prio(request));
+
 	engine->request_stats.runnable++;
+	atomic_dec(&engine->request_stats.queued);
 
 	GEM_BUG_ON(!engine->execlists.first);
 	GEM_BUG_ON(list_empty(&request->priotree.link));
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 54d2ad1c8daa..616066f536c9 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -339,6 +339,14 @@ struct intel_engine_cs {
 	struct drm_i915_gem_object *default_state;
 
 	struct {
+		/**
+		 * @queued: Number of submitted requests with dependencies.
+		 *
+		 * Count of requests waiting for dependencies before they can be
+		 * submitted to the backend.
+		 */
+		atomic_t queued;
+
 		/**
 		 * @runnable: Number of runnable requests sent to the backend.
 		 *
-- 
2.14.1

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