[igt-dev] [PATCH i-g-t 2/2] i915/gem_exec_latency: Add another variant of waiter latency

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

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 tests/i915/gem_exec_latency.c | 81 +++++++++++++++++++++++++++++++++++
 1 file changed, 81 insertions(+)

diff --git a/tests/i915/gem_exec_latency.c b/tests/i915/gem_exec_latency.c
index e88fbbc6a..fd4ceb4d6 100644
--- a/tests/i915/gem_exec_latency.c
+++ b/tests/i915/gem_exec_latency.c
@@ -490,6 +490,83 @@ static void execution_latency(int i915, unsigned int ring, const char *name)
 	gem_close(i915, obj.handle);
 }
 
+static void wakeup_latency(int i915, unsigned int ring, const char *name)
+{
+	struct drm_i915_gem_exec_object2 obj = {
+		.handle = gem_create(i915, 4095),
+	};
+	struct drm_i915_gem_execbuffer2 execbuf = {
+		.buffers_ptr = to_user_pointer(&obj),
+		.buffer_count = 1,
+		.flags = ring | LOCAL_I915_EXEC_NO_RELOC | LOCAL_I915_EXEC_HANDLE_LUT,
+	};
+	const unsigned int mmio_base = 0x2000;
+	const unsigned int cs_timestamp = mmio_base + 0x358;
+	volatile uint32_t *timestamp;
+	struct igt_mean wakeup;
+	uint32_t *cs, *result;
+
+	timestamp =
+		(volatile uint32_t *)((volatile char *)igt_global_mmio + cs_timestamp);
+
+	obj.handle = gem_create(i915, 4096);
+	obj.flags = EXEC_OBJECT_PINNED;
+	result = gem_mmap__wc(i915, obj.handle, 0, 4096, PROT_WRITE);
+
+	cs = result;
+
+	*cs++ = 0x24 << 23 | 2; /* SRM */
+	*cs++ = cs_timestamp;
+	*cs++ = 4096 - 16 * 4;
+	*cs++ = 0;
+
+	*cs++ = MI_BATCH_BUFFER_START | 1;
+	*cs++ = 0;
+	*cs++ = 0;
+
+	*cs++ = 0x24 << 23 | 2; /* SRM */
+	*cs++ = cs_timestamp;
+	*cs++ = 4096 - 16 * 4 + 4;
+	*cs++ = 0;
+	*cs++ = 0xa << 23;
+
+	cs = result + 1024 - 16;
+
+	{
+		struct sched_param p = { .sched_priority = 99 };
+		sched_setscheduler(0, SCHED_FIFO | SCHED_RESET_ON_FORK, &p);
+	}
+
+	igt_mean_init(&wakeup);
+	igt_until_timeout(2) {
+		uint32_t end;
+
+		igt_fork(child, 1) {
+			result[4] = MI_BATCH_BUFFER_START | 1;
+			cs[0] = 0;
+
+			gem_execbuf(i915, &execbuf);
+
+			while (!cs[0])
+				;
+			result[4] = 0;
+			__sync_synchronize();
+		}
+		gem_sync(i915, obj.handle);
+		end = *timestamp;
+
+		igt_mean_add(&wakeup, (end - cs[1]) * rcs_clock);
+		igt_waitchildren();
+	}
+	igt_info("%s Wakeup latency: %.2f±%.2fms [%.2f, %.2f]\n", name,
+		 1e-6 * igt_mean_get(&wakeup),
+		 1e-6 * sqrt(igt_mean_get_variance(&wakeup)),
+		 1e-6 * wakeup.min, 1e-6 * wakeup.max);
+
+	munmap(result, 4096);
+	gem_close(i915, obj.handle);
+}
+
 static void
 __submit_spin(int fd, igt_spin_t *spin, unsigned int flags)
 {
@@ -942,6 +1019,10 @@ igt_main
 					execution_latency(device,
 							  e->exec_id | e->flags,
 							  e->name);
+				igt_subtest_f("%s-wakeup-latency", e->name)
+					wakeup_latency(device,
+							e->exec_id | e->flags,
+							e->name);
 
 				igt_subtest_f("%s-live-dispatch-queued", e->name)
 					latency_on_ring(device,
-- 
2.20.1

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