Now that we are careful to always force-restore contexts upon rewinding
(where necessary), we can restore our optimisation to skip over
completed active execlists when dequeuing.
Referenecs: 35f3fd8182ba ("drm/i915/execlists: Workaround switching back to a completed context")
References: 8ab3a3812aa9 ("drm/i915/gt: Incrementally check for rewinding")
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
---
.../drm/i915/gt/intel_execlists_submission.c | 33 ++++++++++---------
1 file changed, 17 insertions(+), 16 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
index 325da35a3238..dff2fad8d5e3 100644
--- a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
+++ b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
@@ -1224,12 +1224,20 @@ static void set_preempt_timeout(struct intel_engine_cs *engine,
active_preempt_timeout(engine, rq));
}
+static bool completed(const struct i915_request *rq)
+{
+ if (i915_request_has_sentinel(rq))
+ return false;
+
+ return __i915_request_is_complete(rq);
+}
+
static void execlists_dequeue(struct intel_engine_cs *engine)
{
struct intel_engine_execlists * const execlists = &engine->execlists;
struct i915_request **port = execlists->pending;
struct i915_request ** const last_port = port + execlists->port_mask;
- struct i915_request *last = *execlists->active;
+ struct i915_request *last, * const *active;
struct virtual_engine *ve;
struct rb_node *rb;
bool submit = false;
@@ -1266,21 +1274,15 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
* i.e. we will retrigger preemption following the ack in case
* of trouble.
*
- * In theory we can skip over completed contexts that have not
- * yet been processed by events (as those events are in flight):
- *
- * while ((last = *active) && i915_request_completed(last))
- * active++;
- *
- * However, the GPU cannot handle this as it will ultimately
- * find itself trying to jump back into a context it has just
- * completed and barf.
*/
+ active = execlists->active;
+ while ((last = *active) && completed(last))
+ active++;
if (last) {
- if (__i915_request_is_complete(last)) {
- goto check_secondary;
- } else if (need_preempt(engine, last)) {
+ GEM_BUG_ON(!i915_request_is_active(last));
+
+ if (need_preempt(engine, last)) {
ENGINE_TRACE(engine,
"preempting last=%llx:%lld, prio=%d, hint=%d\n",
last->fence.context,
@@ -1343,7 +1345,6 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
* we hopefully coalesce several updates into a single
* submission.
*/
-check_secondary:
if (!list_is_last(&last->sched.link,
&engine->active.requests)) {
/*
@@ -1548,7 +1549,7 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
* of ordered contexts.
*/
if (submit &&
- memcmp(execlists->active,
+ memcmp(active,
execlists->pending,
(port - execlists->pending) * sizeof(*port))) {
*port = NULL;
@@ -1556,7 +1557,7 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
execlists_schedule_in(*port, port - execlists->pending);
WRITE_ONCE(execlists->yield, -1);
- set_preempt_timeout(engine, *execlists->active);
+ set_preempt_timeout(engine, *active);
execlists_submit_ports(engine);
} else {
ring_set_paused(engine, 0);
--
2.20.1
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