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From: Chris Wilson <chris@chris-wilson.co.uk>
To: intel-gfx@lists.freedesktop.org
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Subject: [Intel-gfx] [PATCH 19/57] drm/i915: Fix the iterative dfs for defering requests
Date: Mon,  1 Feb 2021 08:56:37 +0000
Message-ID: <20210201085715.27435-19-chris@chris-wilson.co.uk> (raw)
In-Reply-To: <20210201085715.27435-1-chris@chris-wilson.co.uk>

The current implementation of walking the children of a deferred
requests lacks the backtracking required to reduce the dfs to linear.
Having pulled it from execlists into the common layer, we can reuse the
dfs code for priority inheritance.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_scheduler.c | 56 +++++++++++++++++++--------
 1 file changed, 40 insertions(+), 16 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_scheduler.c b/drivers/gpu/drm/i915/i915_scheduler.c
index bfd37ee801fd..694ca3a3b563 100644
--- a/drivers/gpu/drm/i915/i915_scheduler.c
+++ b/drivers/gpu/drm/i915/i915_scheduler.c
@@ -466,8 +466,10 @@ void i915_request_set_priority(struct i915_request *rq, int prio)
 void __i915_sched_defer_request(struct intel_engine_cs *engine,
 				struct i915_request *rq)
 {
-	struct list_head *pl;
-	LIST_HEAD(list);
+	struct list_head *pos = &rq->sched.waiters_list;
+	const int prio = rq_prio(rq);
+	struct i915_request *rn;
+	LIST_HEAD(dfs);
 
 	lockdep_assert_held(&engine->active.lock);
 	GEM_BUG_ON(!test_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags));
@@ -477,14 +479,11 @@ void __i915_sched_defer_request(struct intel_engine_cs *engine,
 	 * to those that are waiting upon it. So we traverse its chain of
 	 * waiters and move any that are earlier than the request to after it.
 	 */
-	pl = lookup_priolist(engine, rq_prio(rq));
+	rq->sched.dfs.prev = NULL;
 	do {
-		struct i915_dependency *p;
-
-		GEM_BUG_ON(i915_request_is_active(rq));
-		list_move_tail(&rq->sched.link, pl);
-
-		for_each_waiter(p, rq) {
+		list_for_each_continue(pos, &rq->sched.waiters_list) {
+			struct i915_dependency *p =
+				list_entry(pos, typeof(*p), wait_link);
 			struct i915_request *w =
 				container_of(p->waiter, typeof(*w), sched);
 
@@ -500,19 +499,44 @@ void __i915_sched_defer_request(struct intel_engine_cs *engine,
 				   __i915_request_has_started(w) &&
 				   !__i915_request_is_complete(rq));
 
-			if (!i915_request_is_ready(w))
+			if (!i915_request_in_priority_queue(w))
 				continue;
 
-			if (rq_prio(w) < rq_prio(rq))
+			/*
+			 * We also need to reorder within the same priority.
+			 *
+			 * This is unlike priority-inheritance, where if the
+			 * signaler already has a higher priority [earlier
+			 * deadline] than us, we can ignore as it will be
+			 * scheduled first. If a waiter already has the
+			 * same priority, we still have to push it to the end
+			 * of the list. This unfortunately means we cannot
+			 * use the rq_deadline() itself as a 'visited' bit.
+			 */
+			if (rq_prio(w) < prio)
 				continue;
 
-			GEM_BUG_ON(rq_prio(w) > rq_prio(rq));
-			GEM_BUG_ON(i915_request_is_active(w));
-			list_move_tail(&w->sched.link, &list);
+			GEM_BUG_ON(rq_prio(w) != prio);
+
+			/* Remember our position along this branch */
+			rq = stack_push(w, rq, pos);
+			pos = &rq->sched.waiters_list;
 		}
 
-		rq = list_first_entry_or_null(&list, typeof(*rq), sched.link);
-	} while (rq);
+		/* Note list is reversed for waiters wrt signal hierarchy */
+		GEM_BUG_ON(rq->engine != engine);
+		GEM_BUG_ON(!i915_request_in_priority_queue(rq));
+		list_move(&rq->sched.link, &dfs);
+
+		/* Track our visit, and prevent duplicate processing */
+		clear_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
+	} while ((rq = stack_pop(rq, &pos)));
+
+	pos = lookup_priolist(engine, prio);
+	list_for_each_entry_safe(rq, rn, &dfs, sched.link) {
+		set_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
+		list_add_tail(&rq->sched.link, pos);
+	}
 }
 
 static void queue_request(struct intel_engine_cs *engine,
-- 
2.20.1

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  parent reply index

Thread overview: 103+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-01  8:56 [Intel-gfx] [PATCH 01/57] drm/i915/gt: Restrict the GT clock override to just Icelake Chris Wilson
2021-02-01  8:56 ` [Intel-gfx] [PATCH 02/57] drm/i915/selftests: Exercise relative mmio paths to non-privileged registers Chris Wilson
2021-02-01 14:34   ` Mika Kuoppala
2021-02-01  8:56 ` [Intel-gfx] [PATCH 03/57] drm/i915/selftests: Exercise cross-process context isolation Chris Wilson
2021-02-01 16:37   ` Mika Kuoppala
2021-02-01  8:56 ` [Intel-gfx] [PATCH 04/57] drm/i915: Protect against request freeing during cancellation on wedging Chris Wilson
2021-02-02  9:55   ` Mika Kuoppala
2021-02-01  8:56 ` [Intel-gfx] [PATCH 05/57] drm/i915: Take rcu_read_lock for querying fence's driver/timeline names Chris Wilson
2021-02-02 18:33   ` Mika Kuoppala
2021-02-01  8:56 ` [Intel-gfx] [PATCH 06/57] drm/i915/gt: Always flush the submission queue on checking for idle Chris Wilson
2021-02-01  8:56 ` [Intel-gfx] [PATCH 07/57] drm/i915/gt: Move engine setup out of set_default_submission Chris Wilson
2021-02-02 11:57   ` Tvrtko Ursulin
2021-02-01  8:56 ` [Intel-gfx] [PATCH 08/57] drm/i915/gt: Move submission_method into intel_gt Chris Wilson
2021-02-02 12:03   ` Tvrtko Ursulin
2021-02-02 12:18     ` Chris Wilson
2021-02-01  8:56 ` [Intel-gfx] [PATCH 09/57] drm/i915: Replace engine->schedule() with a known request operation Chris Wilson
2021-02-01  8:56 ` [Intel-gfx] [PATCH 10/57] drm/i915: Restructure priority inheritance Chris Wilson
2021-02-01  8:56 ` [Intel-gfx] [PATCH 11/57] drm/i915/selftests: Measure set-priority duration Chris Wilson
2021-02-01  8:56 ` [Intel-gfx] [PATCH 12/57] drm/i915/selftests: Exercise priority inheritance around an engine loop Chris Wilson
2021-02-01  8:56 ` [Intel-gfx] [PATCH 13/57] drm/i915/selftests: Force a rewind if at first we don't succeed Chris Wilson
2021-02-01  8:56 ` [Intel-gfx] [PATCH 14/57] drm/i915: Improve DFS for priority inheritance Chris Wilson
2021-02-01  8:56 ` [Intel-gfx] [PATCH 15/57] drm/i915: Extract request submission from execlists Chris Wilson
2021-02-01  8:56 ` [Intel-gfx] [PATCH 16/57] drm/i915: Extract request rewinding " Chris Wilson
2021-02-02 13:08   ` Tvrtko Ursulin
2021-02-01  8:56 ` [Intel-gfx] [PATCH 17/57] drm/i915: Extract request suspension from the execlists Chris Wilson
2021-02-02 13:15   ` Tvrtko Ursulin
2021-02-02 13:26     ` Chris Wilson
2021-02-02 13:32       ` Tvrtko Ursulin
2021-02-02 13:27     ` Chris Wilson
2021-02-01  8:56 ` [Intel-gfx] [PATCH 18/57] drm/i915: Extract the ability to defer and rerun a request later Chris Wilson
2021-02-02 13:18   ` Tvrtko Ursulin
2021-02-01  8:56 ` Chris Wilson [this message]
2021-02-02 14:10   ` [Intel-gfx] [PATCH 19/57] drm/i915: Fix the iterative dfs for defering requests Tvrtko Ursulin
2021-02-01  8:56 ` [Intel-gfx] [PATCH 20/57] drm/i915: Wrap access to intel_engine.active Chris Wilson
2021-02-04 11:07   ` Tvrtko Ursulin
2021-02-04 11:18     ` Chris Wilson
2021-02-04 11:56       ` Chris Wilson
2021-02-04 12:08         ` Tvrtko Ursulin
2021-02-01  8:56 ` [Intel-gfx] [PATCH 21/57] drm/i915: Move common active lists from engine to i915_scheduler Chris Wilson
2021-02-04 11:12   ` Tvrtko Ursulin
2021-02-01  8:56 ` [Intel-gfx] [PATCH 22/57] drm/i915: Move scheduler queue Chris Wilson
2021-02-04 11:19   ` Tvrtko Ursulin
2021-02-04 11:32     ` Chris Wilson
2021-02-04 11:40     ` Chris Wilson
2021-02-01  8:56 ` [Intel-gfx] [PATCH 23/57] drm/i915: Move tasklet from execlists to sched Chris Wilson
2021-02-04 14:06   ` Tvrtko Ursulin
2021-02-01  8:56 ` [Intel-gfx] [PATCH 24/57] drm/i915/gt: Only kick the scheduler on timeslice/preemption change Chris Wilson
2021-02-04 14:09   ` Tvrtko Ursulin
2021-02-04 14:43     ` Chris Wilson
2021-02-01  8:56 ` [Intel-gfx] [PATCH 25/57] drm/i915: Move submit_request to i915_sched_engine Chris Wilson
2021-02-04 14:13   ` Tvrtko Ursulin
2021-02-04 14:45     ` Chris Wilson
2021-02-01  8:56 ` [Intel-gfx] [PATCH 26/57] drm/i915: Move finding the current active request to the scheduler Chris Wilson
2021-02-04 14:30   ` Tvrtko Ursulin
2021-02-04 14:59     ` Chris Wilson
2021-02-01  8:56 ` [Intel-gfx] [PATCH 27/57] drm/i915: Show execlists queues when dumping state Chris Wilson
2021-02-04 15:04   ` Tvrtko Ursulin
2021-02-01  8:56 ` [Intel-gfx] [PATCH 28/57] drm/i915: Wrap i915_request_use_semaphores() Chris Wilson
2021-02-04 15:05   ` Tvrtko Ursulin
2021-02-01  8:56 ` [Intel-gfx] [PATCH 29/57] drm/i915: Move scheduler flags Chris Wilson
2021-02-04 15:14   ` Tvrtko Ursulin
2021-02-04 16:05     ` Chris Wilson
2021-02-01  8:56 ` [Intel-gfx] [PATCH 30/57] drm/i915: Move timeslicing flag to scheduler Chris Wilson
2021-02-04 15:18   ` Tvrtko Ursulin
2021-02-04 16:11     ` Chris Wilson
2021-02-05  9:48       ` Tvrtko Ursulin
2021-02-01  8:56 ` [Intel-gfx] [PATCH 31/57] drm/i915/gt: Declare when we enabled timeslicing Chris Wilson
2021-02-04 15:26   ` Tvrtko Ursulin
2021-02-01  8:56 ` [Intel-gfx] [PATCH 32/57] drm/i915: Move needs-breadcrumb flags to scheduler Chris Wilson
2021-02-04 15:28   ` Tvrtko Ursulin
2021-02-04 16:12     ` Chris Wilson
2021-02-01  8:56 ` [Intel-gfx] [PATCH 33/57] drm/i915: Move busywaiting control to the scheduler Chris Wilson
2021-02-04 15:32   ` Tvrtko Ursulin
2021-02-01  8:56 ` [Intel-gfx] [PATCH 34/57] drm/i915: Move preempt-reset flag " Chris Wilson
2021-02-04 15:34   ` Tvrtko Ursulin
2021-02-01  8:56 ` [Intel-gfx] [PATCH 35/57] drm/i915: Replace priolist rbtree with a skiplist Chris Wilson
2021-02-01  8:56 ` [Intel-gfx] [PATCH 36/57] drm/i915: Wrap cmpxchg64 with try_cmpxchg64() helper Chris Wilson
2021-02-01  8:56 ` [Intel-gfx] [PATCH 37/57] drm/i915: Fair low-latency scheduling Chris Wilson
2021-02-01  8:56 ` [Intel-gfx] [PATCH 38/57] drm/i915/gt: Specify a deadline for the heartbeat Chris Wilson
2021-02-01  8:56 ` [Intel-gfx] [PATCH 39/57] drm/i915: Extend the priority boosting for the display with a deadline Chris Wilson
2021-02-01  8:56 ` [Intel-gfx] [PATCH 40/57] drm/i915/gt: Support virtual engine queues Chris Wilson
2021-02-01  8:56 ` [Intel-gfx] [PATCH 41/57] drm/i915: Move saturated workload detection back to the context Chris Wilson
2021-02-01  8:57 ` [Intel-gfx] [PATCH 42/57] drm/i915: Bump default timeslicing quantum to 5ms Chris Wilson
2021-02-01  8:57 ` [Intel-gfx] [PATCH 43/57] drm/i915/gt: Delay taking irqoff for execlists submission Chris Wilson
2021-02-01  8:57 ` [Intel-gfx] [PATCH 44/57] drm/i915/gt: Wrap intel_timeline.has_initial_breadcrumb Chris Wilson
2021-02-01  8:57 ` [Intel-gfx] [PATCH 45/57] drm/i915/gt: Track timeline GGTT offset separately from subpage offset Chris Wilson
2021-02-01  8:57 ` [Intel-gfx] [PATCH 46/57] drm/i915/gt: Add timeline "mode" Chris Wilson
2021-02-01  8:57 ` [Intel-gfx] [PATCH 47/57] drm/i915/gt: Use indices for writing into relative timelines Chris Wilson
2021-02-01  8:57 ` [Intel-gfx] [PATCH 48/57] drm/i915/selftests: Exercise relative timeline modes Chris Wilson
2021-02-01  8:57 ` [Intel-gfx] [PATCH 49/57] drm/i915/gt: Use ppHWSP for unshared non-semaphore related timelines Chris Wilson
2021-02-01  8:57 ` [Intel-gfx] [PATCH 50/57] Restore "drm/i915: drop engine_pin/unpin_breadcrumbs_irq" Chris Wilson
2021-02-01  8:57 ` [Intel-gfx] [PATCH 51/57] drm/i915/gt: Couple tasklet scheduling for all CS interrupts Chris Wilson
2021-02-01  8:57 ` [Intel-gfx] [PATCH 52/57] drm/i915/gt: Support creation of 'internal' rings Chris Wilson
2021-02-01  8:57 ` [Intel-gfx] [PATCH 53/57] drm/i915/gt: Use client timeline address for seqno writes Chris Wilson
2021-02-01  8:57 ` [Intel-gfx] [PATCH 54/57] drm/i915/gt: Infrastructure for ring scheduling Chris Wilson
2021-02-01  8:57 ` [Intel-gfx] [PATCH 55/57] drm/i915/gt: Implement ring scheduler for gen4-7 Chris Wilson
2021-02-01  8:57 ` [Intel-gfx] [PATCH 56/57] drm/i915/gt: Enable ring scheduling for gen5-7 Chris Wilson
2021-02-01  8:57 ` [Intel-gfx] [PATCH 57/57] drm/i915: Support secure dispatch on gen6/gen7 Chris Wilson
2021-02-01 14:13 ` [Intel-gfx] ✗ Fi.CI.CHECKPATCH: warning for series starting with [01/57] drm/i915/gt: Restrict the GT clock override to just Icelake Patchwork
2021-02-01 14:15 ` [Intel-gfx] ✗ Fi.CI.SPARSE: " Patchwork
2021-02-01 14:15 ` [Intel-gfx] [PATCH 01/57] " Mika Kuoppala
2021-02-01 14:41 ` [Intel-gfx] ✓ Fi.CI.BAT: success for series starting with [01/57] " Patchwork
2021-02-01 19:33 ` [Intel-gfx] ✗ Fi.CI.IGT: failure " Patchwork

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