[igt-dev] [PATCH i-g-t 1/1] i915/gem_scheduler: Ensure submission order in manycontexts

[Matthew Brost]

With GuC submission contexts can get reordered (compared to submission
order), if contexts get reordered the sequential nature of the batches
releasing the next batch's semaphore in function timesliceN() get broken
resulting in the test taking much longer than if should. e.g. Every
contexts needs to be timesliced to release the next batch. Corking the
first submission until all the batches have been submitted should ensure
submission order.

Signed-off-by: Matthew Brost <matthew.brost at intel.com>
---
 tests/i915/gem_exec_schedule.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/tests/i915/gem_exec_schedule.c b/tests/i915/gem_exec_schedule.c
index f03842478..41f2591a5 100644
--- a/tests/i915/gem_exec_schedule.c
+++ b/tests/i915/gem_exec_schedule.c
@@ -597,12 +597,13 @@ static void timesliceN(int i915, const intel_ctx_cfg_t *cfg,
 	struct drm_i915_gem_execbuffer2 execbuf  = {
 		.buffers_ptr = to_user_pointer(&obj),
 		.buffer_count = 1,
-		.flags = engine | I915_EXEC_FENCE_OUT,
+		.flags = engine | I915_EXEC_FENCE_OUT | I915_EXEC_FENCE_SUBMIT,
 	};
 	uint32_t *result =
 		gem_mmap__device_coherent(i915, obj.handle, 0, sz, PROT_READ);
 	const intel_ctx_t *ctx;
 	int fence[count];
+	IGT_CORK_FENCE(cork);
 
 	/*
 	 * Create a pair of interlocking batches, that ping pong
@@ -614,6 +615,17 @@ static void timesliceN(int i915, const intel_ctx_cfg_t *cfg,
 	igt_require(gem_scheduler_has_timeslicing(i915));
 	igt_require(intel_gen(intel_get_drm_devid(i915)) >= 8);
 
+	/*
+	 * With GuC submission contexts can get reordered (compared to
+	 * submission order), if contexts get reordered the sequential
+	 * nature of the batches releasing the next batch's semaphore gets
+	 * broken resulting in the test taking much longer than it should (e.g.
+	 * every context needs to be timesliced to release the next batch).
+	 * Corking the first submission until all batches have been
+	 * submitted should ensure submission order.
+	 */
+	execbuf.rsvd2 = igt_cork_plug(&cork, i915);
+
 	/* No coupling between requests; free to timeslice */
 
 	for (int i = 0; i < count; i++) {
@@ -624,8 +636,10 @@ static void timesliceN(int i915, const intel_ctx_cfg_t *cfg,
 		intel_ctx_destroy(i915, ctx);
 
 		fence[i] = execbuf.rsvd2 >> 32;
+		execbuf.rsvd2 >>= 32;
 	}
 
+	igt_cork_unplug(&cork);
 	gem_sync(i915, obj.handle);
 	gem_close(i915, obj.handle);
 
-- 
2.28.0