[Impeller] GPU frame timings summarization. (#136408)

Allow processing GPU start and end events to get processed by flutter driver. To figure out whether or not this works we'll ship in on CI :)

packages/flutter_driver/lib/src/driver/gpu_sumarizer.dart

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'percentile_utils.dart';
+import 'timeline.dart';
+
+/// Summarizes [GpuSumarizer]s corresponding to GPU start and end events.
+class GpuSumarizer {
+  /// Creates a RasterCacheSummarizer given the timeline events.
+  GpuSumarizer(List<TimelineEvent> gpuEvents) {
+    for (final TimelineEvent event in gpuEvents) {
+      final Object? value = event.arguments!['FrameTimeMS'];
+      if (value is String) {
+        final double? parsedValue = double.tryParse(value);
+        if (parsedValue != null) {
+          _frameTimes.add(parsedValue);
+        }
+      }
+    }
+  }
+
+  /// Whether or not this event is a GPU event.
+  static const Set<String> kGpuEvents = <String>{'GPUTracer'};
+
+  final List<double> _frameTimes = <double>[];
+
+  /// Computes the average GPU time recorded.
+  double computeAverageGPUTime() => _computeAverage(_frameTimes);
+
+  /// The [percentile]-th percentile GPU time recorded.
+  double computePercentileGPUTime(double percentile) {
+    if (_frameTimes.isEmpty) {
+      return 0;
+    }
+    return findPercentile(_frameTimes, percentile);
+  }
+
+  /// Compute the worst GPU time recorded.
+  double computeWorstGPUTime() => _computeWorst(_frameTimes);
+
+  static double _computeAverage(List<double> values) {
+    if (values.isEmpty) {
+      return 0;
+    }
+
+    double total = 0;
+    for (final double data in values) {
+      total += data;
+    }
+    return total / values.length;
+  }
+
+  static double _computeWorst(List<double> values) {
+    if (values.isEmpty) {
+      return 0;
+    }
+
+    values.sort();
+    return values.last;
+  }
+}

packages/flutter_driver/lib/src/driver/timeline_summary.dart

@@ -11,6 +11,7 @@ import 'package:path/path.dart' as path;
 import 'common.dart';
 import 'frame_request_pending_latency_summarizer.dart';
 import 'gc_summarizer.dart';
+import 'gpu_sumarizer.dart';
 import 'percentile_utils.dart';
 import 'profiling_summarizer.dart';
 import 'raster_cache_summarizer.dart';
@@ -275,6 +276,7 @@ class TimelineSummary {
     final GCSummarizer gcSummarizer = _gcSummarizer();
     final RefreshRateSummary refreshRateSummary = RefreshRateSummary(vsyncEvents: _extractNamedEvents(kUIThreadVsyncProcessEvent));
     final FrameRequestPendingLatencySummarizer frameRequestPendingLatencySummarizer = _frameRequestPendingLatencySummarizer();
+    final GpuSumarizer gpuSummarizer = _gpuSumarizer();
 
     final Map<String, dynamic> timelineSummary = <String, dynamic>{
       'average_frame_build_time_millis': computeAverageFrameBuildTimeMillis(),
@@ -336,6 +338,10 @@ class TimelineSummary {
       '90hz_frame_percentage': refreshRateSummary.percentageOf90HzFrames,
       '120hz_frame_percentage': refreshRateSummary.percentageOf120HzFrames,
       'illegal_refresh_rate_frame_count': refreshRateSummary.framesWithIllegalRefreshRate.length,
+      'average_gpu_frame_time': gpuSummarizer.computeAverageGPUTime(),
+      '90th_percentile_gpu_frame_time': gpuSummarizer.computePercentileGPUTime(90.0),
+      '99th_percentile_gpu_frame_time': gpuSummarizer.computePercentileGPUTime(99.0),
+      'worst_gpu_frame_time': gpuSummarizer.computeWorstGPUTime(),
     };
 
     timelineSummary.addAll(profilingSummary);
@@ -507,4 +513,6 @@ class TimelineSummary {
   FrameRequestPendingLatencySummarizer _frameRequestPendingLatencySummarizer() => FrameRequestPendingLatencySummarizer(_extractNamedEvents(kFrameRequestPendingEvent));
 
   GCSummarizer _gcSummarizer() => GCSummarizer.fromEvents(_extractEventsWithNames(kGCRootEvents));
+
+  GpuSumarizer _gpuSumarizer() => GpuSumarizer(_extractEventsWithNames(GpuSumarizer.kGpuEvents));
 }

packages/flutter_driver/test/src/gpu_summarizer_test.dart

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter_driver/flutter_driver.dart';
+import 'package:flutter_driver/src/driver/gpu_sumarizer.dart';
+
+import '../common.dart';
+
+TimelineEvent newGPUTraceEvent(double ms) => TimelineEvent(<String, dynamic>{
+  'name': 'GPUStart',
+  'ph': 'b',
+  'args': <String, String>{
+    'FrameTimeMS': ms.toString()
+  },
+});
+
+void main() {
+  test('Can process GPU frame times.', () {
+    final GpuSumarizer summarizer = GpuSumarizer(<TimelineEvent>[
+      newGPUTraceEvent(4.233),
+      newGPUTraceEvent(7.22),
+      newGPUTraceEvent(9.1),
+      newGPUTraceEvent(40.23),
+    ]);
+
+    expect(summarizer.computeAverageGPUTime(), closeTo(15.19, 0.1));
+    expect(summarizer.computePercentileGPUTime(50.0), closeTo(9.1, 0.1));
+    expect(summarizer.computeWorstGPUTime(), 40.23);
+  });
+}

packages/flutter_driver/test/src/real_tests/timeline_summary_test.dart

@@ -528,6 +528,10 @@ void main() {
             'average_frame_request_pending_latency': 2000.0,
             '90th_percentile_frame_request_pending_latency': 3000.0,
             '99th_percentile_frame_request_pending_latency': 3000.0,
+            'average_gpu_frame_time': 0,
+            '90th_percentile_gpu_frame_time': 0,
+            '99th_percentile_gpu_frame_time': 0,
+            'worst_gpu_frame_time': 0,
           },
         );
       });
@@ -659,6 +663,10 @@ void main() {
           'average_frame_request_pending_latency': 2000.0,
           '90th_percentile_frame_request_pending_latency': 3000.0,
           '99th_percentile_frame_request_pending_latency': 3000.0,
+          'average_gpu_frame_time': 0,
+          '90th_percentile_gpu_frame_time': 0,
+          '99th_percentile_gpu_frame_time': 0,
+          'worst_gpu_frame_time': 0,
         });
       });
     });