[Intel-gfx] [PATCH v5 1/3] drm/i915: Get active pending request for given context

[Ankit Navik]

This patch gives us the active pending request count which is yet
to be submitted to the GPU.

V2:
 * Change 64-bit to atomic for request count. (Tvrtko Ursulin)

V3:
 * Remove mutex for request count.
 * Rebase.
 * Fixes hitting underflow for predictive request. (Tvrtko Ursulin)

V4:
 * Rebase.

V5:
 * Rebase.

Cc: Vipin Anand <vipin.anand at intel.com>
Signed-off-by: Ankit Navik <ankit.p.navik at intel.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_context.c       | 1 +
 drivers/gpu/drm/i915/gem/i915_gem_context_types.h | 5 +++++
 drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c    | 2 ++
 drivers/gpu/drm/i915/gt/intel_lrc.c               | 3 +++
 4 files changed, 11 insertions(+)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
index 7b01f46..3fd8e73 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
@@ -464,6 +464,7 @@ i915_gem_create_context(struct drm_i915_private *i915, unsigned int flags)
 	}
 
 	trace_i915_context_create(ctx);
+	atomic_set(&ctx->req_cnt, 0);
 
 	return ctx;
 }
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context_types.h b/drivers/gpu/drm/i915/gem/i915_gem_context_types.h
index fe97b8b..6caa6a2 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context_types.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context_types.h
@@ -175,6 +175,11 @@ struct i915_gem_context {
 	 * per vm, which may be one per context or shared with the global GTT)
 	 */
 	struct radix_tree_root handles_vma;
+
+	/** req_cnt: tracks the pending commands, based on which we decide to
+	 * go for low/medium/high load configuration of the GPU.
+	 */
+	atomic_t req_cnt;
 };
 
 #endif /* __I915_GEM_CONTEXT_TYPES_H__ */
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
index e969018..9d9286d 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
@@ -2640,6 +2640,8 @@ i915_gem_do_execbuffer(struct drm_device *dev,
 	if (eb.batch->private)
 		intel_engine_pool_mark_active(eb.batch->private, eb.request);
 
+	atomic_inc(&eb.gem_context->req_cnt);
+
 	trace_i915_request_queue(eb.request, eb.batch_flags);
 	err = eb_submit(&eb);
 err_request:
diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
index d0088d0..4911b63 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -1708,6 +1708,9 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
 
 				submit = true;
 				last = rq;
+
+				if (atomic_read(&rq->gem_context->req_cnt) > 0)
+					atomic_dec(&rq->gem_context->req_cnt);
 			}
 		}
 
-- 
2.7.4