drm/i915/execlists: Cache the last priolist lookup

Avoid the repeated rbtree lookup for each request as we unwind them by
tracking the last priolist.

v2: Fix up my unhelpful suggestion of using default_priolist.

Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170928193910.17988-4-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 303bb2c..7d6da13 100644 (file)
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -358,25 +358,31 @@ static void unwind_wa_tail(struct drm_i915_gem_request *rq)
 static void unwind_incomplete_requests(struct intel_engine_cs *engine)
 {
        struct drm_i915_gem_request *rq, *rn;
+       struct i915_priolist *uninitialized_var(p);
+       int last_prio = I915_PRIORITY_INVALID;
 
        lockdep_assert_held(&engine->timeline->lock);
 
        list_for_each_entry_safe_reverse(rq, rn,
                                         &engine->timeline->requests,
                                         link) {
-               struct i915_priolist *p;
-
                if (i915_gem_request_completed(rq))
                        return;
 
                __i915_gem_request_unsubmit(rq);
                unwind_wa_tail(rq);
 
-               p = lookup_priolist(engine,
-                                   &rq->priotree,
-                                   rq->priotree.priority);
-               list_add(&rq->priotree.link,
-                        &ptr_mask_bits(p, 1)->requests);
+               GEM_BUG_ON(rq->priotree.priority == I915_PRIORITY_INVALID);
+               if (rq->priotree.priority != last_prio) {
+                       p = lookup_priolist(engine,
+                                           &rq->priotree,
+                                           rq->priotree.priority);
+                       p = ptr_mask_bits(p, 1);
+
+                       last_prio = rq->priotree.priority;
+               }
+
+               list_add(&rq->priotree.link, &p->requests);
        }
 }