Collecting LatencyInfo in telemetry

tools/perf/metrics/smoothness.py

Index: tools/perf/metrics/smoothness.py
diff --git a/tools/perf/metrics/smoothness.py b/tools/perf/metrics/smoothness.py
index 6d304097223287dcf789eaa53e36b663db0aa79f..47dc5e21df3d06f7f791729f21959ee6f0b6dce0 100644
--- a/tools/perf/metrics/smoothness.py
+++ b/tools/perf/metrics/smoothness.py
@@ -64,8 +64,10 @@ class SmoothnessMetric(Metric):
                         for action in self._actions ]
 
     renderer_process = timeline_model.GetRendererProcessFromTab(tab)
+    browser_main_thread = timeline_model.GetBrowserMainThread()
+
     self._stats = rendering_stats.RenderingStats(
-        renderer_process, timeline_ranges)
+        renderer_process, browser_main_thread, timeline_ranges)
 
     if not self._stats.frame_times:
       raise NotEnoughFramesError()
@@ -77,6 +79,33 @@ class SmoothnessMetric(Metric):
     self._stats = stats
 
   def AddResults(self, tab, results):
+    if self._stats.mouse_wheel_latency:
+      mean_mouse_wheel_latency = statistics.ArithmeticMean(
+          self._stats.mouse_wheel_latency, len(self._stats.mouse_wheel_latency))
+      results.Add('mean_mouse_wheel_latency', 'ms',
+                  round(mean_mouse_wheel_latency, 3))
+      results.Add('mouse_wheel_latency_75%', 'ms',
+                  statistics.Percentile(self._stats.mouse_wheel_latency, 75.0) )
+
+    if self._stats.gesture_scroll_latency:
+      mean_gesture_scroll_latency = statistics.ArithmeticMean(
+          self._stats.gesture_scroll_latency,
+          len(self._stats.gesture_scroll_latency))
+      results.Add('mean_gesture_scroll_latency', 'ms',
+                  round(mean_gesture_scroll_latency, 3))
+      results.Add('gesture_scroll_latency_75%', 'ms',

[Rick Byers, 2014/01/21 13:57:17]

Has there been any discussion of what the right metric to use is here?  To me
75th percentile doesn't seem much more useful than median.  Can we bump this up
to 90th or 95th without the results on our pagesets getting too noisy?

[Yufeng Shen (Slow to review), 2014/01/22 23:23:35]

Done.

[Rick Byers, 2014/01/23 00:57:05]

Thanks.  How consistent does this tend to be from run-to-run on Android?  On
Aura I know we have inconsistent scheduling that'll add noise, but hopefully we
can get this to be relatively stable on Android.

+                  statistics.Percentile(self._stats.gesture_scroll_latency,
+                                        75.0) )
+
+    if self._stats.touch_scroll_latency:
+      mean_touch_scroll_latency = statistics.ArithmeticMean(
+          self._stats.touch_scroll_latency,
+          len(self._stats.touch_scroll_latency))
+      results.Add('mean_touch_scroll_latency', 'ms',
+                  round(mean_touch_scroll_latency, 3))
+      results.Add('touch_scroll_latency_75%', 'ms',
+                  statistics.Percentile(self._stats.touch_scroll_latency,
+                                        75.0) )
     # List of raw frame times.
     results.Add('frame_times', 'ms', self._stats.frame_times)