[igt-dev] [PATCH i-g-t v2] i915/perf_pmu: Exercise I915_PMU_SOFTWARE_GT_AWAKE_TIME

[Chris Wilson]

Measure the sample gt-awake time while each engine and every engine is
busy. They should all report the same duration, the elapsed runtime of
the batch.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin at linux.intel.com>
---
 include/drm-uapi/i915_drm.h |  3 ++-
 lib/igt_dummyload.c         | 10 +++++++++
 lib/igt_dummyload.h         |  1 +
 tests/i915/perf_pmu.c       | 43 +++++++++++++++++++++++++++++++++++++
 4 files changed, 56 insertions(+), 1 deletion(-)

diff --git a/include/drm-uapi/i915_drm.h b/include/drm-uapi/i915_drm.h
index ef696d1a5..bf9ea471c 100644
--- a/include/drm-uapi/i915_drm.h
+++ b/include/drm-uapi/i915_drm.h
@@ -177,8 +177,9 @@ enum drm_i915_pmu_engine_sample {
 #define I915_PMU_REQUESTED_FREQUENCY	__I915_PMU_OTHER(1)
 #define I915_PMU_INTERRUPTS		__I915_PMU_OTHER(2)
 #define I915_PMU_RC6_RESIDENCY		__I915_PMU_OTHER(3)
+#define I915_PMU_SOFTWARE_GT_AWAKE_TIME	__I915_PMU_OTHER(4)
 
-#define I915_PMU_LAST I915_PMU_RC6_RESIDENCY
+#define I915_PMU_LAST /* Deprecated - do not use */ I915_PMU_RC6_RESIDENCY
 
 /* Each region is a minimum of 16k, and there are at most 255 of them.
  */
diff --git a/lib/igt_dummyload.c b/lib/igt_dummyload.c
index 4ef79cc4a..b29d12aff 100644
--- a/lib/igt_dummyload.c
+++ b/lib/igt_dummyload.c
@@ -590,6 +590,16 @@ void igt_terminate_spins(void)
 	pthread_mutex_unlock(&list_lock);
 }
 
+void igt_free_spins(int i915)
+{
+	struct igt_spin *iter, *next;
+
+	pthread_mutex_lock(&list_lock);
+	igt_list_for_each_entry_safe(iter, next, &spin_list, link)
+		igt_spin_free(i915, iter);
+	pthread_mutex_unlock(&list_lock);
+}
+
 void igt_unshare_spins(void)
 {
 	struct igt_spin *it, *n;
diff --git a/lib/igt_dummyload.h b/lib/igt_dummyload.h
index 3ece70a50..9e19ffabc 100644
--- a/lib/igt_dummyload.h
+++ b/lib/igt_dummyload.h
@@ -107,6 +107,7 @@ static inline void igt_spin_busywait_until_started(igt_spin_t *spin)
 
 void igt_terminate_spins(void);
 void igt_unshare_spins(void);
+void igt_free_spins(int i915);
 
 enum igt_cork_type {
 	CORK_SYNC_FD = 1,
diff --git a/tests/i915/perf_pmu.c b/tests/i915/perf_pmu.c
index c2b186d39..da06a28b0 100644
--- a/tests/i915/perf_pmu.c
+++ b/tests/i915/perf_pmu.c
@@ -883,6 +883,43 @@ sema_busy(int gem_fd,
 	close(fd[1]);
 }
 
+static void test_awake(int i915)
+{
+	const struct intel_execution_engine2 *e;
+	unsigned long slept;
+	uint64_t val;
+	int fd;
+
+	fd = perf_i915_open(i915, I915_PMU_SOFTWARE_GT_AWAKE_TIME);
+	igt_skip_on(fd < 0);
+
+	/* Check that each engine is captured by the GT wakeref */
+	__for_each_physical_engine(i915, e) {
+		igt_spin_new(i915, .engine = e->flags);
+
+		val = pmu_read_single(fd);
+		slept = measured_usleep(batch_duration_ns / 1000);
+		val = pmu_read_single(fd) - val;
+
+		gem_quiescent_gpu(i915);
+		assert_within_epsilon(val, slept, tolerance);
+	}
+
+	/* And that the total GT wakeref matches walltime not summation */
+	__for_each_physical_engine(i915, e)
+		igt_spin_new(i915, .engine = e->flags);
+
+	val = pmu_read_single(fd);
+	slept = measured_usleep(batch_duration_ns / 1000);
+	val = pmu_read_single(fd) - val;
+
+	gem_quiescent_gpu(i915);
+	assert_within_epsilon(val, slept, tolerance);
+
+	igt_free_spins(i915);
+	close(fd);
+}
+
 #define   MI_WAIT_FOR_PIPE_C_VBLANK (1<<21)
 #define   MI_WAIT_FOR_PIPE_B_VBLANK (1<<11)
 #define   MI_WAIT_FOR_PIPE_A_VBLANK (1<<3)
@@ -2250,6 +2287,12 @@ igt_main
 	igt_subtest("rc6-suspend")
 		test_rc6(fd, TEST_S3);
 
+	/**
+	 * Test GT wakeref tracking (similar to RC0, opposite of RC6)
+	 */
+	igt_subtest("gt-awake")
+		test_awake(fd);
+
 	/**
 	 * Check render nodes are counted.
 	 */
-- 
2.29.2