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drm/i915/execlists: Switch to rb_root_cached

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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@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180629075348.27358-9-chris@chris-wilson.co.uk
This commit is contained in:
Chris Wilson 2018-06-29 08:53:20 +01:00
parent cb4dc8daf4
commit 655250a8d1
4 changed files with 19 additions and 39 deletions
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7
drivers/gpu/drm/i915/intel_engine_cs.c
View File

@ -467,8 +467,7 @@ static void intel_engine_init_execlist(struct intel_engine_cs *engine)
GEM_BUG_ON(execlists_num_ports(execlists) > EXECLIST_MAX_PORTS);
execlists->queue_priority = INT_MIN;
execlists->queue = RB_ROOT;
execlists->first = NULL;
execlists->queue = RB_ROOT_CACHED;
}
/**
@ -1004,7 +1003,7 @@ bool intel_engine_is_idle(struct intel_engine_cs *engine)
}
/* ELSP is empty, but there are ready requests? E.g. after reset */
if (READ_ONCE(engine->execlists.first))
if (!RB_EMPTY_ROOT(&engine->execlists.queue.rb_root))
return false;
/* Ring stopped? */
@ -1540,7 +1539,7 @@ void intel_engine_dump(struct intel_engine_cs *engine,
last = NULL;
count = 0;
drm_printf(m, "\t\tQueue priority: %d\n", execlists->queue_priority);
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);

12
drivers/gpu/drm/i915/intel_guc_submission.c
View File

@ -695,9 +695,6 @@ static bool __guc_dequeue(struct intel_engine_cs *engine)
lockdep_assert_held(&engine->timeline.lock);
rb = execlists->first;
GEM_BUG_ON(rb_first(&execlists->queue) != rb);
if (port_isset(port)) {
if (intel_engine_has_preemption(engine)) {
struct guc_preempt_work *preempt_work =
@ -719,7 +716,7 @@ static bool __guc_dequeue(struct intel_engine_cs *engine)
}
GEM_BUG_ON(port_isset(port));
while (rb) {
while ((rb = rb_first_cached(&execlists->queue))) {
struct i915_priolist *p = to_priolist(rb);
struct i915_request *rq, *rn;
@ -744,15 +741,13 @@ static bool __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);
}
done:
execlists->queue_priority = rb ? to_priolist(rb)->priority : INT_MIN;
execlists->first = rb;
if (submit)
port_assign(port, last);
if (last)
@ -761,7 +756,8 @@ done:
/* We must always keep the beast fed if we have work piled up */
GEM_BUG_ON(port_isset(execlists->port) &&
!execlists_is_active(execlists, EXECLISTS_ACTIVE_USER));
GEM_BUG_ON(execlists->first && !port_isset(execlists->port));
GEM_BUG_ON(rb_first_cached(&execlists->queue) &&
!port_isset(execlists->port));
return submit;
}

32
drivers/gpu/drm/i915/intel_lrc.c
View File

@ -273,7 +273,7 @@ lookup_priolist(struct intel_engine_cs *engine, int prio)
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 = to_priolist(rb);
@ -311,10 +311,7 @@ find_priolist:
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 p;
}
@ -602,9 +599,6 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
* and context switches) submission.
*/
rb = execlists->first;
GEM_BUG_ON(rb_first(&execlists->queue) != rb);
if (last) {
/*
* Don't resubmit or switch until all outstanding
@ -666,7 +660,7 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
last->tail = last->wa_tail;
}
while (rb) {
while ((rb = rb_first_cached(&execlists->queue))) {
struct i915_priolist *p = to_priolist(rb);
struct i915_request *rq, *rn;
@ -725,8 +719,7 @@ 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);
@ -752,14 +745,14 @@ done:
execlists->queue_priority =
port != execlists->port ? rq_prio(last) : INT_MIN;
execlists->first = rb;
if (submit) {
port_assign(port, last);
execlists_submit_ports(engine);
}
/* We must always keep the beast fed if we have work piled up */
GEM_BUG_ON(execlists->first && !port_isset(execlists->port));
GEM_BUG_ON(rb_first_cached(&execlists->queue) &&
!port_isset(execlists->port));
/* Re-evaluate the executing context setup after each preemptive kick */
if (last)
@ -922,8 +915,7 @@ 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 = to_priolist(rb);
list_for_each_entry_safe(rq, rn, &p->requests, sched.link) {
@ -933,8 +925,7 @@ static void execlists_cancel_requests(struct intel_engine_cs *engine)
__i915_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);
@ -943,8 +934,7 @@ static void execlists_cancel_requests(struct intel_engine_cs *engine)
/* Remaining _unready_ requests will be nop'ed when submitted */
execlists->queue_priority = INT_MIN;
execlists->queue = RB_ROOT;
execlists->first = NULL;
execlists->queue = RB_ROOT_CACHED;
GEM_BUG_ON(port_isset(execlists->port));
spin_unlock_irqrestore(&engine->timeline.lock, flags);
@ -1192,7 +1182,7 @@ static void execlists_submit_request(struct i915_request *request)
queue_request(engine, &request->sched, rq_prio(request));
GEM_BUG_ON(!engine->execlists.first);
GEM_BUG_ON(RB_EMPTY_ROOT(&engine->execlists.queue.rb_root));
GEM_BUG_ON(list_empty(&request->sched.link));
submit_queue(engine, rq_prio(request));
@ -2044,7 +2034,7 @@ static void execlists_reset_finish(struct intel_engine_cs *engine)
struct intel_engine_execlists * const execlists = &engine->execlists;
/* 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);
/*

7
drivers/gpu/drm/i915/intel_ringbuffer.h
View File

@ -292,12 +292,7 @@ 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;
/**
* @csb_read: control register for Context Switch buffer