[PATCH 067/118] drm/i915/preemption: Select timeout when scheduling

Chris Wilson chris at chris-wilson.co.uk
Tue Sep 11 19:49:27 UTC 2018


The choice of preemption timeout is determined by the context from which
we trigger the preemption, as such allow the caller to specify the
desired timeout.

Effectively the other choice would be to use the shortest timeout along
the dependency chain. However, given that we would have already
triggered preemption for the dependency chain, we can assume that no
preemption along that chain is more important than the current request,
ergo we need only consider the current timeout. Realising this, we can
then pass control of the preemption timeout to the caller for greater
flexibility.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_gem.c            |   2 +-
 drivers/gpu/drm/i915/i915_request.c        |   2 +-
 drivers/gpu/drm/i915/i915_scheduler.c      |  11 ++-
 drivers/gpu/drm/i915/i915_scheduler.h      |   5 +-
 drivers/gpu/drm/i915/intel_ringbuffer.h    |   3 +-
 drivers/gpu/drm/i915/selftests/intel_lrc.c | 110 ++++++++++++++++++++-
 6 files changed, 123 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 4f91dc9bc9b0..19bfa858c88f 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -571,7 +571,7 @@ static void __fence_set_priority(struct dma_fence *fence,
 	local_bh_disable();
 	rcu_read_lock(); /* RCU serialisation for set-wedged protection */
 	if (engine->schedule)
-		engine->schedule(rq, attr);
+		engine->schedule(rq, attr, 0);
 	rcu_read_unlock();
 	local_bh_enable(); /* kick the tasklets if queues were reprioritised */
 }
diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index 957948bfcf5d..f658f6240030 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -1056,7 +1056,7 @@ void i915_request_add(struct i915_request *request)
 		if (!prev || i915_request_completed(prev))
 			attr.priority |= I915_PRIORITY_NEWCLIENT;
 
-		engine->schedule(request, &attr);
+		engine->schedule(request, &attr, 0);
 	}
 	rcu_read_unlock();
 	i915_sw_fence_commit(&request->submit);
diff --git a/drivers/gpu/drm/i915/i915_scheduler.c b/drivers/gpu/drm/i915/i915_scheduler.c
index 5c34bbdfe405..6937c3f20a65 100644
--- a/drivers/gpu/drm/i915/i915_scheduler.c
+++ b/drivers/gpu/drm/i915/i915_scheduler.c
@@ -240,7 +240,8 @@ sched_lock_engine(struct i915_sched_node *node, struct intel_engine_cs *locked)
 }
 
 static void __i915_schedule(struct i915_request *rq,
-			    const struct i915_sched_attr *attr)
+			    const struct i915_sched_attr *attr,
+			    unsigned int timeout)
 {
 	struct list_head *uninitialized_var(pl);
 	struct intel_engine_cs *engine, *last;
@@ -373,10 +374,12 @@ static void __i915_schedule(struct i915_request *rq,
 	spin_unlock_irq(&engine->timeline.lock);
 }
 
-void i915_schedule(struct i915_request *rq, const struct i915_sched_attr *attr)
+void i915_schedule(struct i915_request *rq,
+		   const struct i915_sched_attr *attr,
+		   unsigned int timeout)
 {
 	spin_lock(&schedule_lock);
-	__i915_schedule(rq, attr);
+	__i915_schedule(rq, attr, timeout);
 	spin_unlock(&schedule_lock);
 }
 
@@ -393,7 +396,7 @@ void i915_schedule_bump_priority(struct i915_request *rq, unsigned int bump)
 
 	attr = rq->sched.attr;
 	attr.priority |= bump;
-	__i915_schedule(rq, &attr);
+	__i915_schedule(rq, &attr, 0);
 
 	spin_unlock_bh(&schedule_lock);
 }
diff --git a/drivers/gpu/drm/i915/i915_scheduler.h b/drivers/gpu/drm/i915/i915_scheduler.h
index 99dc89360c79..95ef42e96aaa 100644
--- a/drivers/gpu/drm/i915/i915_scheduler.h
+++ b/drivers/gpu/drm/i915/i915_scheduler.h
@@ -97,8 +97,9 @@ int i915_sched_node_add_dependency(struct drm_i915_private *i915,
 void i915_sched_node_fini(struct drm_i915_private *i915,
 			  struct i915_sched_node *node);
 
-void i915_schedule(struct i915_request *request,
-		   const struct i915_sched_attr *attr);
+void i915_schedule(struct i915_request *rq,
+		   const struct i915_sched_attr *attr,
+		   unsigned int timeout);
 
 void i915_schedule_bump_priority(struct i915_request *rq, unsigned int bump);
 
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 8eccf1c7aa5f..1a321222f6c8 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -513,7 +513,8 @@ struct intel_engine_cs {
 	 * not be ready to run!
 	 */
 	void		(*schedule)(struct i915_request *request,
-				    const struct i915_sched_attr *attr);
+				    const struct i915_sched_attr *attr,
+				    unsigned int timeout);
 
 	/*
 	 * Cancel all requests on the hardware, or queued for execution.
diff --git a/drivers/gpu/drm/i915/selftests/intel_lrc.c b/drivers/gpu/drm/i915/selftests/intel_lrc.c
index ce91760fdf7c..84d722b9c4e9 100644
--- a/drivers/gpu/drm/i915/selftests/intel_lrc.c
+++ b/drivers/gpu/drm/i915/selftests/intel_lrc.c
@@ -420,7 +420,7 @@ static int live_late_preempt(void *arg)
 		}
 
 		attr.priority = I915_USER_PRIORITY(I915_PRIORITY_MAX);
-		engine->schedule(rq, &attr);
+		engine->schedule(rq, &attr, 0);
 
 		if (!wait_for_spinner(&spin_hi, rq)) {
 			pr_err("High priority context failed to preempt the low priority context\n");
@@ -757,6 +757,113 @@ static int live_preempt_reset(void *arg)
 	return err;
 }
 
+static int live_late_preempt_timeout(void *arg)
+{
+	struct drm_i915_private *i915 = arg;
+	struct i915_gem_context *ctx_hi, *ctx_lo;
+	struct spinner spin_hi, spin_lo;
+	struct intel_engine_cs *engine;
+	enum intel_engine_id id;
+	int err = -ENOMEM;
+
+	if (!HAS_LOGICAL_RING_PREEMPTION(i915))
+		return 0;
+
+	mutex_lock(&i915->drm.struct_mutex);
+
+	if (spinner_init(&spin_hi, i915))
+		goto err_unlock;
+
+	if (spinner_init(&spin_lo, i915))
+		goto err_spin_hi;
+
+	ctx_hi = kernel_context(i915);
+	if (!ctx_hi)
+		goto err_spin_lo;
+
+	ctx_lo = kernel_context(i915);
+	if (!ctx_lo)
+		goto err_ctx_hi;
+
+	for_each_engine(engine, i915, id) {
+		struct i915_request *rq;
+
+		rq = spinner_create_request(&spin_lo, ctx_lo, engine, MI_NOOP);
+		if (IS_ERR(rq)) {
+			err = PTR_ERR(rq);
+			goto err_ctx_lo;
+		}
+
+		i915_request_add(rq);
+		if (!wait_for_spinner(&spin_lo, rq)) {
+			pr_err("First context failed to start\n");
+			goto err_wedged;
+		}
+
+		rq = spinner_create_request(&spin_hi, ctx_hi, engine, MI_NOOP);
+		if (IS_ERR(rq)) {
+			spinner_end(&spin_lo);
+			err = PTR_ERR(rq);
+			goto err_ctx_lo;
+		}
+
+		i915_request_add(rq);
+		if (wait_for_spinner(&spin_hi, rq)) {
+			pr_err("Second context overtook first?\n");
+			goto err_wedged;
+		}
+
+		GEM_TRACE("%s rescheduling (no timeout)\n", engine->name);
+		engine->schedule(rq, &(struct i915_sched_attr){
+				 .priority = I915_USER_PRIORITY(1),
+				 }, 0);
+
+		if (wait_for_spinner(&spin_hi, rq)) {
+			pr_err("High priority context overtook first without an arbitration point?\n");
+			goto err_wedged;
+		}
+
+		GEM_TRACE("%s rescheduling (with timeout)\n", engine->name);
+		engine->schedule(rq, &(struct i915_sched_attr){
+				 .priority = I915_USER_PRIORITY(2),
+				 }, 10 * 1000 /* 10us */);
+
+		if (!wait_for_spinner(&spin_hi, rq)) {
+			pr_err("High priority context failed to force itself in front of the low priority context\n");
+			GEM_TRACE_DUMP();
+			goto err_wedged;
+		}
+
+		spinner_end(&spin_hi);
+		spinner_end(&spin_lo);
+		if (igt_flush_test(i915, I915_WAIT_LOCKED)) {
+			err = -EIO;
+			goto err_ctx_lo;
+		}
+	}
+
+	err = 0;
+err_ctx_lo:
+	kernel_context_close(ctx_lo);
+err_ctx_hi:
+	kernel_context_close(ctx_hi);
+err_spin_lo:
+	spinner_fini(&spin_lo);
+err_spin_hi:
+	spinner_fini(&spin_hi);
+err_unlock:
+	igt_flush_test(i915, I915_WAIT_LOCKED);
+	mutex_unlock(&i915->drm.struct_mutex);
+	return err;
+
+err_wedged:
+	spinner_end(&spin_hi);
+	spinner_end(&spin_lo);
+	i915_gem_set_wedged(i915);
+	err = -EIO;
+	goto err_ctx_lo;
+}
+
 struct live_test {
 	struct drm_i915_private *i915;
 	const char *func;
@@ -1108,6 +1215,7 @@ int intel_execlists_live_selftests(struct drm_i915_private *i915)
 		SUBTEST(live_preempt_hang),
 		SUBTEST(live_preempt_timeout),
 		SUBTEST(live_preempt_reset),
+		SUBTEST(live_late_preempt_timeout),
 		SUBTEST(live_virtual_engine),
 		SUBTEST(live_virtual_bond),
 	};
-- 
2.19.0



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