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Document that missed_frame_build_budget_count is misleading (#132137)

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Fixes https://github.com/flutter/flutter/issues/109745
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Ian Hickson 2023-08-08 15:08:30 -07:00 committed by GitHub
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commit b29069ec0b
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1 changed files with 26 additions and 10 deletions
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36
packages/flutter_driver/lib/src/driver/timeline_summary.dart
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@ -31,7 +31,11 @@ generated by the interaction.
''';
/// The maximum amount of time considered safe to spend for a frame's build
/// phase. Anything past that is in the danger of missing the frame as 60FPS.
/// phase. Anything past that is in the danger of missing the frame at 60FPS.
///
/// This is a hard-coded number and does not take into account the real device
/// frame rate. Prefer using percentiles on the total build or raster time
/// than metrics based on this value.
const Duration kBuildBudget = Duration(milliseconds: 16);
/// The name of the framework frame build events we need to filter or extract.
@ -71,9 +75,14 @@ class TimelineSummary {
/// The number of frames that missed the [kBuildBudget] and therefore are
/// in the danger of missing frames.
int computeMissedFrameBuildBudgetCount([ Duration frameBuildBudget = kBuildBudget ]) => _extractFrameDurations()
.where((Duration duration) => duration > kBuildBudget)
.length;
///
/// This does not take into account the real device frame rate. Prefer using
/// [computePercentileFrameBuildTimeMillis] for evaluating performance.
int computeMissedFrameBuildBudgetCount() {
return _extractFrameDurations()
.where((Duration duration) => duration > kBuildBudget)
.length;
}
/// Average amount of time spent per frame in the engine rasterizer.
///
@ -112,9 +121,14 @@ class TimelineSummary {
/// The number of frames that missed the [kBuildBudget] on the raster thread
/// and therefore are in the danger of missing frames.
int computeMissedFrameRasterizerBudgetCount([ Duration frameBuildBudget = kBuildBudget ]) => _extractGpuRasterizerDrawDurations()
.where((Duration duration) => duration > kBuildBudget)
.length;
///
/// This does not take into account the real device frame rate. Prefer using
/// [computePercentileFrameRasterizerTimeMillis] for evaluating performance.
int computeMissedFrameRasterizerBudgetCount() {
return _extractGpuRasterizerDrawDurations()
.where((Duration duration) => duration > kBuildBudget)
.length;
}
/// The total number of frames recorded in the timeline.
int countFrames() => _extractFrameDurations().length;
@ -156,7 +170,8 @@ class TimelineSummary {
/// See [computeWorstFrameBuildTimeMillis].
/// * "missed_frame_build_budget_count': The number of frames that missed
/// the [kBuildBudget] and therefore are in the danger of missing frames.
/// See [computeMissedFrameBuildBudgetCount].
/// See [computeMissedFrameBuildBudgetCount]. Because [kBuildBudget] is a
/// constant, this does not represent a real missed frame count.
/// * "average_frame_rasterizer_time_millis": Average amount of time spent
/// per frame in the engine rasterizer.
/// See [computeAverageFrameRasterizerTimeMillis].
@ -172,8 +187,9 @@ class TimelineSummary {
/// See [computeWorstFrameRasterizerTimeMillis].
/// * "missed_frame_rasterizer_budget_count": The number of frames that missed
/// the [kBuildBudget] on the raster thread and therefore are in the danger
/// of missing frames.
/// See [computeMissedFrameRasterizerBudgetCount].
/// of missing frames. See [computeMissedFrameRasterizerBudgetCount].
/// Because [kBuildBudget] is a constant, this does not represent a real
/// missed frame count.
/// * "frame_count": The total number of frames recorded in the timeline. This
/// is also the length of the "frame_build_times" and the "frame_begin_times"
/// lists.