[PATCH v4 1/3] drm/i915: Get active pending request for given context

[Ankit Navik <ankit.p.navik@intel.com>]

From: Praveen Diwakar <praveen.diwakar@intel.com>

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.

Cc: Aravindan Muthukumar <aravindan.muthukumar@intel.com>
Cc: Kedar J Karanje <kedar.j.karanje@intel.com>
Cc: Yogesh Marathe <yogesh.marathe@intel.com>
Signed-off-by: Praveen Diwakar <praveen.diwakar@intel.com>
Signed-off-by: Ankit Navik <ankit.p.navik@intel.com>
---
 drivers/gpu/drm/i915/i915_gem_context.c    | 1 +
 drivers/gpu/drm/i915/i915_gem_context.h    | 5 +++++
 drivers/gpu/drm/i915/i915_gem_execbuffer.c | 2 ++
 drivers/gpu/drm/i915/intel_lrc.c           | 3 +++
 4 files changed, 11 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index 280813a..a5876fe 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -453,6 +453,7 @@ i915_gem_create_context(struct drm_i915_private *dev_priv,
 	}
 
 	trace_i915_context_create(ctx);
+	atomic_set(&ctx->req_cnt, 0);
 
 	return ctx;
 }
diff --git a/drivers/gpu/drm/i915/i915_gem_context.h b/drivers/gpu/drm/i915/i915_gem_context.h
index ca150a7..c940168 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.h
+++ b/drivers/gpu/drm/i915/i915_gem_context.h
@@ -227,6 +227,11 @@ struct i915_gem_context {
 	 * context close.
 	 */
 	struct list_head handles_list;
+
+	/** 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;
 };
 
 static inline bool i915_gem_context_is_closed(const struct i915_gem_context *ctx)
diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 02adcaf..a38963b 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -2475,6 +2475,8 @@ i915_gem_do_execbuffer(struct drm_device *dev,
 	 */
 	eb.request->batch = eb.batch;
 
+	atomic_inc(&eb.ctx->req_cnt);
+
 	trace_i915_request_queue(eb.request, eb.batch_flags);
 	err = eb_submit(&eb);
 err_request:
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 34a0866..d0af37d 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -780,6 +780,9 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
 
 			last = rq;
 			submit = true;
+
+			if (atomic_read(&rq->gem_context->req_cnt) > 0)
+				atomic_dec(&rq->gem_context->req_cnt);
 		}
 
 		rb_erase_cached(&p->node, &execlists->queue);
-- 
2.7.4

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