[Intel-gfx] [PATCH 35/42] drm/i915/selftests: Measure set-priority duration

[Chris Wilson <chris@chris-wilson.co.uk>]

As a topological sort, we expect it to run in linear graph time,
O(V+E). In removing the recursion, it is no longer a DFS but rather a
BFS, and performs as O(VE). Let's demonstrate how bad this is with a few
examples, and build a few test cases to verify a potential fix.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_scheduler.c         |   4 +
 .../drm/i915/selftests/i915_live_selftests.h  |   1 +
 .../drm/i915/selftests/i915_perf_selftests.h  |   1 +
 .../gpu/drm/i915/selftests/i915_scheduler.c   | 530 ++++++++++++++++++
 4 files changed, 536 insertions(+)
 create mode 100644 drivers/gpu/drm/i915/selftests/i915_scheduler.c

diff --git a/drivers/gpu/drm/i915/i915_scheduler.c b/drivers/gpu/drm/i915/i915_scheduler.c
index 45e000c257db..3c1a0b001746 100644
--- a/drivers/gpu/drm/i915/i915_scheduler.c
+++ b/drivers/gpu/drm/i915/i915_scheduler.c
@@ -565,6 +565,10 @@ void i915_sched_node_retire(struct i915_sched_node *node)
 	spin_unlock_irq(&node->lock);
 }
 
+#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
+#include "selftests/i915_scheduler.c"
+#endif
+
 static void i915_global_scheduler_shrink(void)
 {
 	kmem_cache_shrink(global.slab_dependencies);
diff --git a/drivers/gpu/drm/i915/selftests/i915_live_selftests.h b/drivers/gpu/drm/i915/selftests/i915_live_selftests.h
index a92c0e9b7e6b..2200a5baa68e 100644
--- a/drivers/gpu/drm/i915/selftests/i915_live_selftests.h
+++ b/drivers/gpu/drm/i915/selftests/i915_live_selftests.h
@@ -26,6 +26,7 @@ selftest(gt_mocs, intel_mocs_live_selftests)
 selftest(gt_pm, intel_gt_pm_live_selftests)
 selftest(gt_heartbeat, intel_heartbeat_live_selftests)
 selftest(requests, i915_request_live_selftests)
+selftest(scheduler, i915_scheduler_live_selftests)
 selftest(active, i915_active_live_selftests)
 selftest(objects, i915_gem_object_live_selftests)
 selftest(mman, i915_gem_mman_live_selftests)
diff --git a/drivers/gpu/drm/i915/selftests/i915_perf_selftests.h b/drivers/gpu/drm/i915/selftests/i915_perf_selftests.h
index c2389f8a257d..137e35283fee 100644
--- a/drivers/gpu/drm/i915/selftests/i915_perf_selftests.h
+++ b/drivers/gpu/drm/i915/selftests/i915_perf_selftests.h
@@ -17,5 +17,6 @@
  */
 selftest(engine_cs, intel_engine_cs_perf_selftests)
 selftest(request, i915_request_perf_selftests)
+selftest(scheduler, i915_scheduler_perf_selftests)
 selftest(blt, i915_gem_object_blt_perf_selftests)
 selftest(region, intel_memory_region_perf_selftests)
diff --git a/drivers/gpu/drm/i915/selftests/i915_scheduler.c b/drivers/gpu/drm/i915/selftests/i915_scheduler.c
new file mode 100644
index 000000000000..98d29fa8f5f8
--- /dev/null
+++ b/drivers/gpu/drm/i915/selftests/i915_scheduler.c
@@ -0,0 +1,530 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2020 Intel Corporation
+ */
+
+#include "i915_selftest.h"
+
+#include "gt/intel_context.h"
+#include "gt/selftest_engine_heartbeat.h"
+#include "selftests/igt_spinner.h"
+
+static void scheduling_disable(struct intel_engine_cs *engine)
+{
+	engine->props.preempt_timeout_ms = 0;
+	engine->props.timeslice_duration_ms = 0;
+
+	st_engine_heartbeat_disable(engine);
+}
+
+static void scheduling_enable(struct intel_engine_cs *engine)
+{
+	st_engine_heartbeat_enable(engine);
+
+	engine->props.preempt_timeout_ms =
+		engine->defaults.preempt_timeout_ms;
+	engine->props.timeslice_duration_ms =
+		engine->defaults.timeslice_duration_ms;
+}
+
+static int first_engine(struct drm_i915_private *i915,
+			int (*chain)(struct intel_engine_cs *engine,
+				     unsigned long param,
+				     void (*fn)(struct i915_request *rq,
+						unsigned long v,
+						unsigned long e)),
+			unsigned long param,
+			void (*fn)(struct i915_request *rq,
+				   unsigned long v, unsigned long e))
+{
+	struct intel_engine_cs *engine;
+
+	for_each_uabi_engine(engine, i915) {
+		if (!intel_engine_has_scheduler(engine))
+			continue;
+
+		return chain(engine, param, fn);
+	}
+
+	return 0;
+}
+
+static int all_engines(struct drm_i915_private *i915,
+		       int (*chain)(struct intel_engine_cs *engine,
+				    unsigned long param,
+				    void (*fn)(struct i915_request *rq,
+					       unsigned long v,
+					       unsigned long e)),
+		       unsigned long param,
+		       void (*fn)(struct i915_request *rq,
+				  unsigned long v, unsigned long e))
+{
+	struct intel_engine_cs *engine;
+	int err;
+
+	for_each_uabi_engine(engine, i915) {
+		if (!intel_engine_has_scheduler(engine))
+			continue;
+
+		err = chain(engine, param, fn);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+static bool check_context_order(struct intel_engine_cs *engine)
+{
+	u64 last_seqno, last_context;
+	unsigned long count;
+	bool result = false;
+	struct rb_node *rb;
+	int last_prio;
+
+	/* We expect the execution order to follow ascending fence-context */
+	spin_lock_irq(&engine->active.lock);
+
+	count = 0;
+	last_context = 0;
+	for (rb = rb_first_cached(&engine->execlists.queue); rb; rb = rb_next(rb)) {
+		struct i915_priolist *p = rb_entry(rb, typeof(*p), node);
+		struct i915_request *rq;
+
+		priolist_for_each_request(rq, p) {
+			if (rq->fence.context < last_context ||
+			    (rq->fence.context == last_context &&
+			     rq->fence.seqno < last_seqno)) {
+				pr_err("[%lu] %llx:%lld [prio:%d] after %llx:%lld [prio:%d]\n",
+				       count,
+				       rq->fence.context,
+				       rq->fence.seqno,
+				       rq_prio(rq),
+				       last_context,
+				       last_seqno,
+				       last_prio);
+				goto out_unlock;
+			}
+
+			last_context = rq->fence.context;
+			last_seqno = rq->fence.seqno;
+			last_prio = rq_prio(rq);
+			count++;
+		}
+	}
+	result = true;
+out_unlock:
+	spin_unlock_irq(&engine->active.lock);
+
+	return result;
+}
+
+static int __single_chain(struct intel_engine_cs *engine, unsigned long length,
+			  void (*fn)(struct i915_request *rq,
+				     unsigned long v, unsigned long e))
+{
+	struct intel_context *ce;
+	struct igt_spinner spin;
+	struct i915_request *rq;
+	unsigned long count;
+	unsigned long min;
+	int err = 0;
+
+	scheduling_disable(engine);
+
+	if (igt_spinner_init(&spin, engine->gt)) {
+		err = -ENOMEM;
+		goto err_heartbeat;
+	}
+
+	ce = intel_context_create(engine);
+	if (IS_ERR(ce)) {
+		err = PTR_ERR(ce);
+		goto err_spin;
+	}
+	ce->ring = __intel_context_ring_size(SZ_512K);
+
+	rq = igt_spinner_create_request(&spin, ce, MI_NOOP);
+	if (IS_ERR(rq)) {
+		err = PTR_ERR(rq);
+		goto err_context;
+	}
+	i915_request_add(rq);
+	min = ce->ring->size - ce->ring->space;
+
+	count = 1;
+	while (count < length && ce->ring->space > min) {
+		rq = intel_context_create_request(ce);
+		if (IS_ERR(rq)) {
+			err = PTR_ERR(rq);
+			break;
+		}
+		i915_request_add(rq);
+		count++;
+	}
+
+	tasklet_disable(&engine->execlists.tasklet);
+	local_bh_disable();
+	fn(rq, count, count - 1);
+	if (!check_context_order(engine))
+		err = -EINVAL;
+	local_bh_enable();
+	tasklet_enable(&engine->execlists.tasklet);
+
+	igt_spinner_end(&spin);
+err_context:
+	intel_context_put(ce);
+err_spin:
+	igt_spinner_fini(&spin);
+err_heartbeat:
+	scheduling_enable(engine);
+	return err;
+}
+
+static int __wide_chain(struct intel_engine_cs *engine, unsigned long width,
+			void (*fn)(struct i915_request *rq,
+				   unsigned long v, unsigned long e))
+{
+	struct intel_context **ce;
+	struct i915_request **rq;
+	struct igt_spinner spin;
+	unsigned long count;
+	unsigned long i, j;
+	int err = 0;
+
+	scheduling_disable(engine);
+
+	if (igt_spinner_init(&spin, engine->gt)) {
+		err = -ENOMEM;
+		goto err_heartbeat;
+	}
+
+	ce = kmalloc_array(width, sizeof(*ce), GFP_KERNEL);
+	if (!ce) {
+		err = -ENOMEM;
+		goto err_spin;
+	}
+
+	for (i = 0; i < width; i++) {
+		ce[i] = intel_context_create(engine);
+		if (IS_ERR(ce[i])) {
+			err = PTR_ERR(ce[i]);
+			width = i;
+			goto err_context;
+		}
+	}
+
+	rq = kmalloc_array(width, sizeof(*rq), GFP_KERNEL);
+	if (!rq) {
+		err = -ENOMEM;
+		goto err_context;
+	}
+
+	rq[0] = igt_spinner_create_request(&spin, ce[0], MI_NOOP);
+	if (IS_ERR(rq[0])) {
+		err = PTR_ERR(rq[0]);
+		goto err_free;
+	}
+	i915_request_add(rq[0]);
+
+	count = 0;
+	for (i = 1; i < width; i++) {
+		GEM_BUG_ON(i915_request_completed(rq[0]));
+
+		rq[i] = intel_context_create_request(ce[i]);
+		if (IS_ERR(rq[i])) {
+			err = PTR_ERR(rq[i]);
+			break;
+		}
+		for (j = 0; j < i; j++) {
+			err = i915_request_await_dma_fence(rq[i],
+							   &rq[j]->fence);
+			if (err)
+				break;
+			count++;
+		}
+		i915_request_add(rq[i]);
+	}
+
+	tasklet_disable(&engine->execlists.tasklet);
+	local_bh_disable();
+	fn(rq[i - 1], i, count);
+	if (!check_context_order(engine))
+		err = -EINVAL;
+	local_bh_enable();
+	tasklet_enable(&engine->execlists.tasklet);
+
+	igt_spinner_end(&spin);
+err_free:
+	kfree(rq);
+err_context:
+	for (i = 0; i < width; i++)
+		intel_context_put(ce[i]);
+	kfree(ce);
+err_spin:
+	igt_spinner_fini(&spin);
+err_heartbeat:
+	scheduling_enable(engine);
+	return err;
+}
+
+static int __inv_chain(struct intel_engine_cs *engine, unsigned long width,
+		       void (*fn)(struct i915_request *rq,
+				  unsigned long v, unsigned long e))
+{
+	struct intel_context **ce;
+	struct i915_request **rq;
+	struct igt_spinner spin;
+	unsigned long count;
+	unsigned long i, j;
+	int err = 0;
+
+	scheduling_disable(engine);
+
+	if (igt_spinner_init(&spin, engine->gt)) {
+		err = -ENOMEM;
+		goto err_heartbeat;
+	}
+
+	ce = kmalloc_array(width, sizeof(*ce), GFP_KERNEL);
+	if (!ce) {
+		err = -ENOMEM;
+		goto err_spin;
+	}
+
+	for (i = 0; i < width; i++) {
+		ce[i] = intel_context_create(engine);
+		if (IS_ERR(ce[i])) {
+			err = PTR_ERR(ce[i]);
+			width = i;
+			goto err_context;
+		}
+	}
+
+	rq = kmalloc_array(width, sizeof(*rq), GFP_KERNEL);
+	if (!rq) {
+		err = -ENOMEM;
+		goto err_context;
+	}
+
+	rq[0] = igt_spinner_create_request(&spin, ce[0], MI_NOOP);
+	if (IS_ERR(rq[0])) {
+		err = PTR_ERR(rq[0]);
+		goto err_free;
+	}
+	i915_request_add(rq[0]);
+
+	count = 0;
+	for (i = 1; i < width; i++) {
+		GEM_BUG_ON(i915_request_completed(rq[0]));
+
+		rq[i] = intel_context_create_request(ce[i]);
+		if (IS_ERR(rq[i])) {
+			err = PTR_ERR(rq[i]);
+			break;
+		}
+		for (j = i; j > 0; j--) {
+			err = i915_request_await_dma_fence(rq[i],
+							   &rq[j - 1]->fence);
+			if (err)
+				break;
+			count++;
+		}
+		i915_request_add(rq[i]);
+	}
+
+	tasklet_disable(&engine->execlists.tasklet);
+	local_bh_disable();
+	fn(rq[i - 1], i, count);
+	if (!check_context_order(engine))
+		err = -EINVAL;
+	local_bh_enable();
+	tasklet_enable(&engine->execlists.tasklet);
+
+	igt_spinner_end(&spin);
+err_free:
+	kfree(rq);
+err_context:
+	for (i = 0; i < width; i++)
+		intel_context_put(ce[i]);
+	kfree(ce);
+err_spin:
+	igt_spinner_fini(&spin);
+err_heartbeat:
+	scheduling_enable(engine);
+	return err;
+}
+
+static int igt_single(struct drm_i915_private *i915,
+		      void (*fn)(struct i915_request *rq,
+				 unsigned long v, unsigned long e))
+{
+	return all_engines(i915, __single_chain, 17, fn);
+}
+
+static int igt_wide(struct drm_i915_private *i915,
+		    void (*fn)(struct i915_request *rq,
+			       unsigned long v, unsigned long e))
+{
+	return all_engines(i915, __wide_chain, 17, fn);
+}
+
+static int igt_inv(struct drm_i915_private *i915,
+		   void (*fn)(struct i915_request *rq,
+			      unsigned long v, unsigned long e))
+{
+	return all_engines(i915, __inv_chain, 17, fn);
+}
+
+static void igt_priority(struct i915_request *rq,
+			 unsigned long v, unsigned long e)
+{
+	i915_request_set_priority(rq, I915_PRIORITY_BARRIER);
+	GEM_BUG_ON(rq_prio(rq) != I915_PRIORITY_BARRIER);
+}
+
+static int igt_priority_single(void *arg)
+{
+	return igt_single(arg, igt_priority);
+}
+
+static int igt_priority_wide(void *arg)
+{
+	return igt_wide(arg, igt_priority);
+}
+
+static int igt_priority_inv(void *arg)
+{
+	return igt_inv(arg, igt_priority);
+}
+
+int i915_scheduler_live_selftests(struct drm_i915_private *i915)
+{
+	static const struct i915_subtest tests[] = {
+		SUBTEST(igt_priority_single),
+		SUBTEST(igt_priority_wide),
+		SUBTEST(igt_priority_inv),
+	};
+
+	return i915_subtests(tests, i915);
+}
+
+static int chains(struct drm_i915_private *i915,
+		  int (*chain)(struct drm_i915_private *i915,
+			       unsigned long length,
+			       void (*fn)(struct i915_request *rq,
+					  unsigned long v, unsigned long e)),
+		  void (*fn)(struct i915_request *rq,
+			     unsigned long v, unsigned long e))
+{
+	unsigned long x[] = { 1, 4, 16, 64, 128, 256, 512, 1024, 4096 };
+	int i, err;
+
+	for (i = 0; i < ARRAY_SIZE(x); i++) {
+		IGT_TIMEOUT(end_time);
+
+		err = chain(i915, x[i], fn);
+		if (err)
+			return err;
+
+		if (__igt_timeout(end_time, NULL))
+			break;
+	}
+
+	return 0;
+}
+
+static int single_chain(struct drm_i915_private *i915,
+			unsigned long length,
+			void (*fn)(struct i915_request *rq,
+				   unsigned long v, unsigned long e))
+{
+	return first_engine(i915, __single_chain, length, fn);
+}
+
+static int single(struct drm_i915_private *i915,
+		  void (*fn)(struct i915_request *rq,
+			     unsigned long v, unsigned long e))
+{
+	return chains(i915, single_chain, fn);
+}
+
+static int wide_chain(struct drm_i915_private *i915,
+		      unsigned long width,
+		      void (*fn)(struct i915_request *rq,
+				 unsigned long v, unsigned long e))
+{
+	return first_engine(i915, __wide_chain, width, fn);
+}
+
+static int wide(struct drm_i915_private *i915,
+		void (*fn)(struct i915_request *rq,
+			   unsigned long v, unsigned long e))
+{
+	return chains(i915, wide_chain, fn);
+}
+
+static int inv_chain(struct drm_i915_private *i915,
+		     unsigned long width,
+		     void (*fn)(struct i915_request *rq,
+				unsigned long v, unsigned long e))
+{
+	return first_engine(i915, __inv_chain, width, fn);
+}
+
+static int inv(struct drm_i915_private *i915,
+	       void (*fn)(struct i915_request *rq,
+			  unsigned long v, unsigned long e))
+{
+	return chains(i915, inv_chain, fn);
+}
+
+static void report(const char *what, unsigned long v, unsigned long e, u64 dt)
+{
+	pr_info("(%4lu, %7lu), %s:%10lluns\n", v, e, what, dt);
+}
+
+static u64 __set_priority(struct i915_request *rq, int prio)
+{
+	u64 dt;
+
+	preempt_disable();
+	dt = ktime_get_raw_fast_ns();
+	i915_request_set_priority(rq, prio);
+	dt = ktime_get_raw_fast_ns() - dt;
+	preempt_enable();
+
+	return dt;
+}
+
+static void set_priority(struct i915_request *rq,
+			 unsigned long v, unsigned long e)
+{
+	report("set-priority", v, e, __set_priority(rq, I915_PRIORITY_BARRIER));
+}
+
+static int single_priority(void *arg)
+{
+	return single(arg, set_priority);
+}
+
+static int wide_priority(void *arg)
+{
+	return wide(arg, set_priority);
+}
+
+static int inv_priority(void *arg)
+{
+	return inv(arg, set_priority);
+}
+
+int i915_scheduler_perf_selftests(struct drm_i915_private *i915)
+{
+	static const struct i915_subtest tests[] = {
+		SUBTEST(single_priority),
+		SUBTEST(wide_priority),
+		SUBTEST(inv_priority),
+	};
+
+	return i915_subtests(tests, i915);
+}
-- 
2.20.1

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