[PATCH 5/5] drm/i915: Warn if request allocation stalls

[Chris Wilson]

---
 drivers/gpu/drm/i915/i915_request.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index abd4dacbab8e..78db48aa573d 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -647,6 +647,8 @@ i915_request_alloc(struct intel_engine_cs *engine, struct i915_gem_context *ctx)
 	rq = kmem_cache_alloc(i915->requests,
 			      GFP_KERNEL | __GFP_RETRY_MAYFAIL | __GFP_NOWARN);
 	if (unlikely(!rq)) {
+		ktime_t start = ktime_get();
+
 		i915_retire_requests(i915);
 
 		/* Ratelimit ourselves to prevent oom from malicious clients */
@@ -671,6 +673,10 @@ i915_request_alloc(struct intel_engine_cs *engine, struct i915_gem_context *ctx)
 			ret = -ENOMEM;
 			goto err_unreserve;
 		}
+
+		WARN(ktime_ms_delta(ktime_get(), start) > 500,
+		     "request allocation delayed for %lldms\n",
+		     ktime_ms_delta(ktime_get(), start));
 	}
 
 	rq->rcustate = get_state_synchronize_rcu();
-- 
2.19.0