[PATCH 10/16] drm/i915/execlists: Switch to rb_root_cached
Chris Wilson
chris at chris-wilson.co.uk
Thu Jan 4 18:26:03 UTC 2018
The kernel recently gained an augmented rbtree with the purpose of
cacheing the leftmost element of the rbtree, a frequent optimisation to
avoid calls to rb_first() which is also employed by the
execlists->queue. Switch from our open-coded cache to the library.
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
drivers/gpu/drm/i915/intel_engine_cs.c | 7 +++----
drivers/gpu/drm/i915/intel_guc_submission.c | 10 +++-------
drivers/gpu/drm/i915/intel_lrc.c | 30 ++++++++++-------------------
drivers/gpu/drm/i915/intel_ringbuffer.h | 7 +------
4 files changed, 17 insertions(+), 37 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
index ebdcbcbacb3c..5f6aa260bd4e 100644
--- a/drivers/gpu/drm/i915/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/intel_engine_cs.c
@@ -418,8 +418,7 @@ static void intel_engine_init_execlist(struct intel_engine_cs *engine)
BUILD_BUG_ON_NOT_POWER_OF_2(execlists_num_ports(execlists));
GEM_BUG_ON(execlists_num_ports(execlists) > EXECLIST_MAX_PORTS);
- execlists->queue = RB_ROOT;
- execlists->first = NULL;
+ execlists->queue = RB_ROOT_CACHED;
}
/**
@@ -1501,7 +1500,7 @@ bool intel_engine_is_idle(struct intel_engine_cs *engine)
return false;
/* ELSP is empty, but there are ready requests? */
- if (READ_ONCE(engine->execlists.first))
+ if (!RB_EMPTY_ROOT(&engine->execlists.queue.rb_root))
return false;
/* Ring stopped? */
@@ -1870,7 +1869,7 @@ void intel_engine_dump(struct intel_engine_cs *engine,
spin_lock_irq(&engine->timeline->lock);
list_for_each_entry(rq, &engine->timeline->requests, link)
print_request(m, rq, "\t\tE ");
- for (rb = execlists->first; rb; rb = rb_next(rb)) {
+ for (rb = rb_first_cached(&execlists->queue); rb; rb = rb_next(rb)) {
struct i915_priolist *p =
rb_entry(rb, typeof(*p), node);
diff --git a/drivers/gpu/drm/i915/intel_guc_submission.c b/drivers/gpu/drm/i915/intel_guc_submission.c
index 1f3a8786bbdc..d78c066e1ca2 100644
--- a/drivers/gpu/drm/i915/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/intel_guc_submission.c
@@ -681,9 +681,7 @@ static void guc_dequeue(struct intel_engine_cs *engine)
struct rb_node *rb;
spin_lock_irq(&engine->timeline->lock);
- rb = execlists->first;
- GEM_BUG_ON(rb_first(&execlists->queue) != rb);
-
+ rb = rb_first_cached(&execlists->queue);
if (!rb)
goto unlock;
@@ -734,14 +732,12 @@ static void guc_dequeue(struct intel_engine_cs *engine)
submit = true;
}
- rb = rb_next(rb);
- rb_erase(&p->node, &execlists->queue);
+ rb_erase_cached(&p->node, &execlists->queue);
INIT_LIST_HEAD(&p->requests);
if (p->priority != I915_PRIORITY_NORMAL)
kmem_cache_free(engine->i915->priorities, p);
- } while (rb);
+ } while ((rb = rb_first_cached(&execlists->queue)));
done:
- execlists->first = rb;
if (submit) {
port_assign(port, last);
execlists_set_active(execlists, EXECLISTS_ACTIVE_USER);
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 4e150b095a11..144a7e90e773 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -270,7 +270,7 @@ lookup_priolist(struct intel_engine_cs *engine,
find_priolist:
/* most positive priority is scheduled first, equal priorities fifo */
rb = NULL;
- parent = &execlists->queue.rb_node;
+ parent = &execlists->queue.rb_root.rb_node;
while (*parent) {
rb = *parent;
p = rb_entry(rb, typeof(*p), node);
@@ -308,10 +308,7 @@ lookup_priolist(struct intel_engine_cs *engine,
p->priority = prio;
INIT_LIST_HEAD(&p->requests);
rb_link_node(&p->node, rb, parent);
- rb_insert_color(&p->node, &execlists->queue);
-
- if (first)
- execlists->first = &p->node;
+ rb_insert_color_cached(&p->node, &execlists->queue, first);
return ptr_pack_bits(p, first, 1);
}
@@ -544,8 +541,7 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
*/
spin_lock_irq(&engine->timeline->lock);
- rb = execlists->first;
- GEM_BUG_ON(rb_first(&execlists->queue) != rb);
+ rb = rb_first_cached(&execlists->queue);
if (!rb)
goto unlock;
@@ -674,14 +670,12 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
submit = true;
}
- rb = rb_next(rb);
- rb_erase(&p->node, &execlists->queue);
+ rb_erase_cached(&p->node, &execlists->queue);
INIT_LIST_HEAD(&p->requests);
if (p->priority != I915_PRIORITY_NORMAL)
kmem_cache_free(engine->i915->priorities, p);
- } while (rb);
+ } while ((rb = rb_first_cached(&execlists->queue)));
done:
- execlists->first = rb;
if (submit)
port_assign(port, last);
unlock:
@@ -732,8 +726,7 @@ static void execlists_cancel_requests(struct intel_engine_cs *engine)
}
/* Flush the queued requests to the timeline list (for retiring). */
- rb = execlists->first;
- while (rb) {
+ while ((rb = rb_first_cached(&execlists->queue))) {
struct i915_priolist *p = rb_entry(rb, typeof(*p), node);
list_for_each_entry_safe(rq, rn, &p->requests, priotree.link) {
@@ -743,8 +736,7 @@ static void execlists_cancel_requests(struct intel_engine_cs *engine)
__i915_gem_request_submit(rq);
}
- rb = rb_next(rb);
- rb_erase(&p->node, &execlists->queue);
+ rb_erase_cached(&p->node, &execlists->queue);
INIT_LIST_HEAD(&p->requests);
if (p->priority != I915_PRIORITY_NORMAL)
kmem_cache_free(engine->i915->priorities, p);
@@ -752,9 +744,7 @@ static void execlists_cancel_requests(struct intel_engine_cs *engine)
/* Remaining _unready_ requests will be nop'ed when submitted */
-
- execlists->queue = RB_ROOT;
- execlists->first = NULL;
+ execlists->queue = RB_ROOT_CACHED;
GEM_BUG_ON(port_isset(execlists->port));
/*
@@ -967,7 +957,7 @@ static void execlists_submit_request(struct drm_i915_gem_request *request)
insert_request(engine, &request->priotree, request->priotree.priority);
- GEM_BUG_ON(!engine->execlists.first);
+ GEM_BUG_ON(RB_EMPTY_ROOT(&engine->execlists.queue.rb_root));
GEM_BUG_ON(list_empty(&request->priotree.link));
spin_unlock_irqrestore(&engine->timeline->lock, flags);
@@ -1505,7 +1495,7 @@ static int gen8_init_common_ring(struct intel_engine_cs *engine)
execlists->active = 0;
/* After a GPU reset, we may have requests to replay */
- if (execlists->first)
+ if (!RB_EMPTY_ROOT(&execlists->queue.rb_root))
tasklet_schedule(&execlists->tasklet);
return 0;
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index c5ff203e42d6..0b762a4d4612 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -258,12 +258,7 @@ struct intel_engine_execlists {
/**
* @queue: queue of requests, in priority lists
*/
- struct rb_root queue;
-
- /**
- * @first: leftmost level in priority @queue
- */
- struct rb_node *first;
+ struct rb_root_cached queue;
/**
* @fw_domains: forcewake domains for irq tasklet
--
2.15.1
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