[Intel-gfx] [CI 2/8] drm/i915: Retire oldest completed request before allocating next

Chris Wilson chris at chris-wilson.co.uk
Wed Jul 20 08:21:09 UTC 2016


In order to keep the memory allocated for requests reasonably tight, try
to reuse the oldest request (so long as it is completed and has no
external references) for the next allocation.

v2: Throw in a comment to hopefully make sure no one mistakes the
optimistic retirement of the oldest request for simply stealing it.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala at intel.com>
---
 drivers/gpu/drm/i915/i915_gem_request.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_gem_request.c b/drivers/gpu/drm/i915/i915_gem_request.c
index 9e9aa6b725f7..5cbb11ece60a 100644
--- a/drivers/gpu/drm/i915/i915_gem_request.c
+++ b/drivers/gpu/drm/i915/i915_gem_request.c
@@ -226,6 +226,14 @@ __i915_gem_request_alloc(struct intel_engine_cs *engine,
 	if (ret)
 		return ret;
 
+	/* Move the oldest request to the slab-cache (if not in use!) */
+	if (!list_empty(&engine->request_list)) {
+		req = list_first_entry(&engine->request_list,
+				       typeof(*req), list);
+		if (i915_gem_request_completed(req))
+			i915_gem_request_retire(req);
+	}
+
 	req = kmem_cache_zalloc(dev_priv->requests, GFP_KERNEL);
 	if (!req)
 		return -ENOMEM;
-- 
2.8.1



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