frame_times: A list of raw frame times
mean_frame_time: The arithmetic mean of frame times
- mostly_smooth: Whether we hit 60 fps for 95% of all frames
- jank: The absolute discrepancy of frame timestamps
+ percentage_smooth: Percentage of frames that were hitting 60 FPS.
+ frame_time_discrepancy: The absolute discrepancy of frame timestamps
mean_pixels_approximated: The mean percentage of pixels approximated
queueing_durations: The queueing delay between compositor & main threads
def _ComputeFrameTimeMetric(self, page, stats):
"""Returns Values for the frame time metrics.
- This includes the raw and mean frame times, as well as the mostly_smooth
- metric which tracks whether we hit 60 fps for 95% of the frames.
+ This includes the raw and mean frame times, as well as the percentage of
+ frames that were hitting 60 fps.
"""
frame_times = None
mean_frame_time = None
- mostly_smooth = None
+ percentage_smooth = None
none_value_reason = None
if self._HasEnoughFrames(stats.frame_timestamps):
frame_times = FlattenList(stats.frame_times)
mean_frame_time = round(statistics.ArithmeticMean(frame_times), 3)
- # We use 19ms as a somewhat looser threshold, instead of 1000.0/60.0.
- percentile_95 = statistics.Percentile(frame_times, 95.0)
- mostly_smooth = 1.0 if percentile_95 < 19.0 else 0.0
+ # We use 17ms as a somewhat looser threshold, instead of 1000.0/60.0.
+ smooth_threshold = 17.0
+ smooth_count = sum(1 for t in frame_times if t < smooth_threshold)
+ percentage_smooth = float(smooth_count) / len(frame_times) * 100.0
else:
none_value_reason = NOT_ENOUGH_FRAMES_MESSAGE
return (
description='Arithmetic mean of frame times.',
none_value_reason=none_value_reason),
scalar.ScalarValue(
- page, 'mostly_smooth', 'score', mostly_smooth,
- description='Were 95 percent of the frames hitting 60 fps?'
- 'boolean value (1/0).',
+ page, 'percentage_smooth', 'score', percentage_smooth,
+ description='Percentage of frames that were hitting 60 fps.',
none_value_reason=none_value_reason)
)
else:
none_value_reason = NOT_ENOUGH_FRAMES_MESSAGE
return scalar.ScalarValue(
- page, 'jank', 'ms', frame_discrepancy,
+ page, 'frame_time_discrepancy', 'ms', frame_discrepancy,
description='Absolute discrepancy of frame time stamps, where '
'discrepancy is a measure of irregularity. It quantifies '
'the worst jank. For a single pause, discrepancy '