Commit a2dd2ff5 authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915/gt: Skip over completed active execlists, again 



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: 35f3fd81 ("drm/i915/execlists: Workaround switching back to a completed context")
References: 8ab3a381 ("drm/i915/gt: Incrementally check for rewinding")
Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: default avatarMika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210120121718.26435-2-chris@chris-wilson.co.uk
parent aba73826

drivers/gpu/drm/i915/gt/intel_execlists_submission.c

+16 −18
Original line number Diff line number Diff line
@@ -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 +1274,13 @@ 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)) {

		if (need_preempt(engine, last)) {

			ENGINE_TRACE(engine,

				     "preempting last=%llx:%lld, prio=%d, hint=%d\n",

				     last->fence.context,
@@ -1359,9 +1359,7 @@ 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)) {

			if (active[1]) {

				/*

				 * Even if ELSP[1] is occupied and not worthy

				 * of timeslices, our queue might be.
@@ -1562,7 +1560,7 @@ 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;
@@ -1570,7 +1568,7 @@ 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);