[igt-dev] [PATCH i-g-t v2] i915/gem_exec_balancer: Randomise bonded submission

[Chris Wilson]

Randomly submit a paired spinner and its cancellation as a bonded
(submit fence) pair. Apply congestion to the engine with more bonded
pairs to see if the execution order fails. If we prevent a cancellation
from running, then the spinner will remain spinning forever.

v2: Test both immediate submission and fenced submission

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
---
 tests/i915/gem_exec_balancer.c | 172 +++++++++++++++++++++++++++++++++
 1 file changed, 172 insertions(+)

diff --git a/tests/i915/gem_exec_balancer.c b/tests/i915/gem_exec_balancer.c
index 80ae82416..04b14dd3a 100644
--- a/tests/i915/gem_exec_balancer.c
+++ b/tests/i915/gem_exec_balancer.c
@@ -1154,6 +1154,175 @@ static void bonded_semaphore(int i915)
 	gem_context_destroy(i915, ctx);
 }
 
+static void __bonded_dual(int i915,
+			  const struct i915_engine_class_instance *siblings,
+			  unsigned int count,
+			  unsigned int flags,
+			  unsigned long *out)
+#define BD_FENCE 0x1
+#define BD_HOSTILE 0x2
+#define BD_MANY 0x4
+{
+	struct drm_i915_gem_exec_object2 batch = {};
+	struct drm_i915_gem_execbuffer2 execbuf = {
+		.buffers_ptr = to_user_pointer(&batch),
+		.buffer_count = 1,
+	};
+	unsigned long cycles = 0;
+	unsigned int spinner;
+	igt_spin_t *a, *b;
+	int timeline;
+	uint32_t A, B;
+
+	srandom(getpid());
+
+	spinner = IGT_SPIN_POLL_RUN;
+	if (flags & BD_HOSTILE)
+		spinner |= IGT_SPIN_NO_PREEMPTION;
+
+	A = gem_context_create(i915);
+	set_load_balancer(i915, A, siblings, count, NULL);
+	a = igt_spin_new(i915, A, .flags = spinner);
+	igt_spin_end(a);
+	gem_sync(i915, a->handle);
+
+	B = gem_context_create(i915);
+	set_load_balancer(i915, B, siblings, count, NULL);
+	b = igt_spin_new(i915, B, .flags = spinner);
+	igt_spin_end(b);
+	gem_sync(i915, b->handle);
+
+	timeline = sw_sync_timeline_create();
+
+	igt_until_timeout(2) {
+		unsigned int master;
+		int fence;
+
+		master = 1;
+		if (flags & BD_MANY)
+			master = rand() % count + 1;
+
+		fence = -1;
+		if (flags & BD_FENCE)
+			fence = sw_sync_timeline_create_fence(timeline,
+							      cycles + 1);
+
+		igt_spin_reset(a);
+		a->execbuf.flags = master | I915_EXEC_FENCE_OUT;
+		if (fence != -1) {
+			a->execbuf.rsvd2 = fence;
+			a->execbuf.flags |= I915_EXEC_FENCE_IN;
+		}
+		gem_execbuf_wr(i915, &a->execbuf);
+
+		igt_spin_reset(b);
+		b->execbuf.flags = master | I915_EXEC_FENCE_OUT;
+		if (fence != -1) {
+			b->execbuf.rsvd2 = fence;
+			b->execbuf.flags |= I915_EXEC_FENCE_IN;
+		}
+		gem_execbuf_wr(i915, &b->execbuf);
+
+		if (rand() % 1)
+			igt_swap(a, b);
+
+		batch.handle = create_semaphore_to_spinner(i915, a);
+		execbuf.rsvd1 = a->execbuf.rsvd1;
+		execbuf.rsvd2 = a->execbuf.rsvd2 >> 32;
+		do {
+			execbuf.flags = rand() % count + 1;
+		} while (execbuf.flags == master);
+		execbuf.flags |= I915_EXEC_FENCE_SUBMIT;
+		gem_execbuf(i915, &execbuf);
+		gem_close(i915, batch.handle);
+
+		batch.handle = create_semaphore_to_spinner(i915, b);
+		execbuf.rsvd1 = b->execbuf.rsvd1;
+		execbuf.rsvd2 = b->execbuf.rsvd2 >> 32;
+		do {
+			execbuf.flags = rand() % count + 1;
+		} while (execbuf.flags == master);
+		execbuf.flags |= I915_EXEC_FENCE_SUBMIT;
+		gem_execbuf(i915, &execbuf);
+		gem_close(i915, batch.handle);
+
+		if (fence != -1) {
+			sw_sync_timeline_inc(timeline, 1);
+			close(fence);
+		}
+		close(a->execbuf.rsvd2 >> 32);
+		close(b->execbuf.rsvd2 >> 32);
+
+		gem_sync(i915, a->handle);
+		gem_sync(i915, b->handle);
+
+		cycles++;
+	}
+
+	*out = cycles;
+
+	close(timeline);
+
+	igt_spin_free(i915, a);
+	igt_spin_free(i915, b);
+
+	gem_context_destroy(i915, A);
+	gem_context_destroy(i915, B);
+}
+
+static void bonded_dual(int i915)
+{
+	unsigned long *cycles;
+
+	/*
+	 * The purpose of bonded submission is to execute one or more requests
+	 * concurrently. However, the very nature of that requires coordinated
+	 * submission across multiple engines.
+	 */
+	igt_require(gem_scheduler_has_preemption(i915));
+
+	cycles = mmap(0, 4096, PROT_WRITE, MAP_SHARED | MAP_ANON, -1, 0);
+
+	for (int class = 1; class < 32; class++) {
+		struct i915_engine_class_instance *siblings;
+		unsigned int count;
+
+		siblings = list_engines(i915, 1u << class, &count);
+		if (count > 1) {
+			const unsigned int phases[] = {
+				0,
+				BD_FENCE,
+				BD_MANY,
+				BD_HOSTILE,
+				BD_HOSTILE | BD_FENCE,
+			};
+
+			for (int i = 0; i < ARRAY_SIZE(phases); i++) {
+				memset(cycles, 0, 4096);
+				igt_fork(child, count + 1)
+					__bonded_dual(i915,
+						      siblings, count,
+						      phases[i],
+						      &cycles[child]);
+				igt_waitchildren();
+				gem_quiescent_gpu(i915);
+
+				for (int child = 1; child < count + 1; child++)
+					cycles[0] += cycles[child];
+
+				igt_info("%s %s %s submission, %lu cycles\n",
+					 phases[i] & BD_HOSTILE ? "Non-preemptible" : "Preemptible",
+					 phases[i] & BD_MANY ? "many-master" : "single-master",
+					 phases[i] & BD_FENCE ? "fenced" : "immediate",
+					 cycles[0]);
+			}
+		}
+		free(siblings);
+	}
+
+	munmap(cycles, 4096);
+}
+
 static void __bonded_nohang(int i915, uint32_t ctx,
 			    const struct i915_engine_class_instance *siblings,
 			    unsigned int count,
@@ -2284,6 +2453,9 @@ igt_main
 	igt_subtest("bonded-semaphore")
 		bonded_semaphore(i915);
 
+	igt_subtest("bonded-dual")
+		bonded_dual(i915);
+
 	igt_fixture {
 		igt_stop_hang_detector();
 	}
-- 
2.27.0.rc2