| <!DOCTYPE html> |
| <!-- |
| Copyright 2017 The Chromium Authors. All rights reserved. |
| Use of this source code is governed by a BSD-style license that can be |
| found in the LICENSE file. |
| --> |
| |
| <link rel="import" href="/tracing/base/iteration_helpers.html"> |
| <link rel="import" href="/tracing/extras/chrome/estimated_input_latency.html"> |
| <link rel="import" href="/tracing/model/helpers/chrome_model_helper.html"> |
| <link rel="import" href="/tracing/value/histogram.html"> |
| |
| <script> |
| 'use strict'; |
| |
| /** |
| * @fileoverview |
| * This file defines the input latency metric estimated as the maximum |
| * expected queueing time (EQT) in sliding window of size 500ms. |
| * |
| * The EQT is defined as the average queueing time of a hypothetical input |
| * event arriving at a random time in the given time window. |
| * For more information see: |
| * - https://goo.gl/OQ2bX6 |
| * - https://goo.gl/jmWpMl |
| * - https://goo.gl/lga4iO |
| */ |
| tr.exportTo('tr.metrics.sh', function() { |
| // The size of the sliding window is chosen arbitrarily (see |
| // https://goo.gl/lga4iO). |
| const WINDOW_SIZE_MS = 500; |
| const EQT_BOUNDARIES = tr.v.HistogramBinBoundaries |
| .createExponential(0.01, WINDOW_SIZE_MS, 50); |
| |
| /** |
| * Returns true if the slice contains a forced GC event. Some stories force |
| * garbage collection before sampling memory usage. Since a forced GC takes |
| * long time we need to ignore it to avoid biasing the input latency results. |
| */ |
| function containsForcedGC_(slice) { |
| return slice.findTopmostSlicesRelativeToThisSlice( |
| tr.metrics.v8.utils.isForcedGarbageCollectionEvent).length > 0; |
| } |
| |
| /** |
| * @param {string} name Name of the histogram. |
| * @param {string} description Description of the histogram. |
| * @returns {!tr.v.Histogram} |
| */ |
| function createHistogramForEQT_(name, description) { |
| let histogram = new tr.v.Histogram(name, |
| tr.b.Unit.byName.timeDurationInMs_smallerIsBetter, EQT_BOUNDARIES); |
| histogram.customizeSummaryOptions({ |
| avg: false, |
| count: false, |
| max: true, |
| min: false, |
| std: false, |
| sum: false, |
| }); |
| histogram.description = description; |
| return histogram; |
| } |
| |
| /** |
| * Adds the input latency estimated as the maximum expected queueing time |
| * in the sliding time window of size WINDOW_SIZE_MS. |
| * The result histogram contains value per renderer. |
| */ |
| function estimatedInputLatency(values, model) { |
| let chromeHelper = model.getOrCreateHelper( |
| tr.model.helpers.ChromeModelHelper); |
| let totalHistogram = createHistogramForEQT_( |
| `total:${WINDOW_SIZE_MS}ms_window:renderer_eqt`, |
| `The maximum EQT in a ${WINDOW_SIZE_MS}ms sliding window` + |
| ' for a given renderer'); |
| let interactiveHistogram = createHistogramForEQT_( |
| `interactive:${WINDOW_SIZE_MS}ms_window:renderer_eqt`, |
| `The maximum EQT in a ${WINDOW_SIZE_MS}ms sliding window` + |
| ' for a given renderer while the page is interactive'); |
| let rendererHelpers = tr.b.dictionaryValues(chromeHelper.rendererHelpers); |
| for (let rendererHelper of rendererHelpers) { |
| if (rendererHelper.isChromeTracingUI) continue; |
| let tasks = rendererHelper.mainThread.sliceGroup.topLevelSlices |
| .filter(slice => slice.duration > 0 && !containsForcedGC_(slice)) |
| .map(slice => {return {start: slice.start, end: slice.end};}); |
| totalHistogram.addSample( |
| tr.e.chrome.maxExpectedQueueingTimeInSlidingWindow( |
| rendererHelper.mainThread.bounds.min, |
| rendererHelper.mainThread.bounds.max, |
| WINDOW_SIZE_MS, tasks)); |
| let interactiveTimestamps = |
| tr.e.chrome.getInteractiveTimestamps(model).get(rendererHelper.pid); |
| if (interactiveTimestamps.length === 0) continue; |
| if (interactiveTimestamps.length > 1) { |
| // TODO(ulan): Support multiple interactive time windows when |
| // https://crbug.com/692112 is fixed. |
| continue; |
| } |
| let interactiveWindow = |
| tr.b.Range.fromExplicitRange(interactiveTimestamps[0], Infinity) |
| .findIntersection(rendererHelper.mainThread.bounds); |
| interactiveHistogram.addSample( |
| tr.e.chrome.maxExpectedQueueingTimeInSlidingWindow( |
| interactiveWindow.min, interactiveWindow.max, |
| WINDOW_SIZE_MS, tasks)); |
| } |
| values.addHistogram(totalHistogram); |
| values.addHistogram(interactiveHistogram); |
| } |
| |
| tr.metrics.MetricRegistry.register(estimatedInputLatency); |
| |
| return { |
| estimatedInputLatency, |
| }; |
| }); |
| </script> |
