drm/i915: Check for no-op priority changes first

In all likelihood, the priority and node are already in the CPU cache
and by checking them first, we can avoid having to chase the
*request->hwsp for the current breadcrumb.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190513120102.29660-3-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/i915_scheduler.c b/drivers/gpu/drm/i915/i915_scheduler.c
index f32d0ee6d58c42456cf29a12e36f16de7d8685d3..5581c5004ff09e2a858451eafd33494a4b114105 100644 (file)
--- a/drivers/gpu/drm/i915/i915_scheduler.c
+++ b/drivers/gpu/drm/i915/i915_scheduler.c
@@ -200,10 +200,10 @@ static void __i915_schedule(struct i915_sched_node *node,
        lockdep_assert_held(&schedule_lock);
        GEM_BUG_ON(prio == I915_PRIORITY_INVALID);
 
-       if (node_signaled(node))
+       if (prio <= READ_ONCE(node->attr.priority))
                return;
 
-       if (prio <= READ_ONCE(node->attr.priority))
+       if (node_signaled(node))
                return;
 
        stack.signaler = node;