# Macrobenchmarks

Performance benchmarks use either flutter drive or the web benchmark harness.

## Mobile benchmarks

### Cull opacity benchmark

To run the cull opacity benchmark on a device:

```
flutter drive --profile test_driver/cull_opacity_perf.dart
```

Results should be in the file `build/cull_opacity_perf.timeline_summary.json`.

More detailed logs should be in `build/cull_opacity_perf.timeline.json`.

### Cubic bezier benchmark

To run the cubic bezier benchmark on a device:

```
flutter drive --profile test_driver/cubic_bezier_perf.dart
```

Results should be in the file `build/cubic_bezier_perf.timeline_summary.json`.

More detailed logs should be in `build/cubic_bezier_perf.timeline.json`.

### Backdrop filter benchmark

To run the backdrop filter benchmark on a device:

```
flutter drive --profile test_driver/backdrop_filter_perf.dart
```

Results should be in the file `build/backdrop_filter_perf.timeline_summary.json`.

More detailed logs should be in `build/backdrop_filter_perf.timeline.json`.

### Post Backdrop filter benchmark

To run the post-backdrop filter benchmark on a device:

```
flutter drive --profile test_driver/post_backdrop_filter_perf.dart
```

Results should be in the file `build/post_backdrop_filter_perf.timeline_summary.json`.

More detailed logs should be in `build/post_backdrop_filter_perf.timeline.json`.

## Web benchmarks

Web benchmarks are compiled from the same entrypoint in `lib/web_benchmarks.dart`.

### How to write a web benchmark

Create a new file for your benchmark under `lib/src/web`. See `bench_draw_rect.dart`
as an example.

Choose one of the two benchmark types:

* A "raw benchmark" records performance metrics from direct interactions with
  `dart:ui` with no framework. This kind of benchmark is good for benchmarking
  low-level engine primitives, such as layer, picture, and semantics performance.
* A "widget benchmark" records performance metrics using a widget. This kind of
  benchmark is good for measuring the performance of widgets, often together with
  engine work that widget-under-test incurs.
* A "widget build benchmark" records the cost of building a widget from nothing.
  This is different from the "widget benchmark" because typically the latter
  only performs incremental UI updates, such as an animation. In contrast, this
  benchmark pumps an empty frame to clear all previously built widgets and
  rebuilds them from scratch.

For a raw benchmark extend `RawRecorder` (tip: you can start by copying
`bench_draw_rect.dart`).

For a widget benchmark extend `WidgetRecorder` (tip: you can start by copying
`bench_simple_lazy_text_scroll.dart`).

For a widget build benchmark extend `WidgetBuildRecorder` (tip: you can start by copying
`bench_build_material_checkbox.dart`).

Pick a unique benchmark name and class name and add it to the `benchmarks` list
in `lib/web_benchmarks.dart`.

### How to run a web benchmark

Web benchmarks can be run using `flutter run` in debug, profile, and release
modes, using either the HTML or the CanvasKit rendering backend. Note, however,
that running in debug mode will result in worse numbers. Profile mode is useful
for profiling in Chrome DevTools because the numbers are close to release mode
and the profile contains unobfuscated names.

Example:

```
cd dev/benchmarks/macrobenchmarks

# Runs in profile mode using the HTML renderer
flutter run --profile -d web-server lib/web_benchmarks.dart

# Runs in profile mode using the CanvasKit renderer
flutter run --dart-define=FLUTTER_WEB_USE_SKIA=true --profile -d web-server lib/web_benchmarks.dart
```

You can also run all benchmarks exactly like the devicelab runs them:

```
cd dev/devicelab

# Runs using the HTML renderer
../../bin/cache/dart-sdk/bin/dart bin/run.dart -t bin/tasks/web_benchmarks_html.dart

# Runs using the CanvasKit renderer
../../bin/cache/dart-sdk/bin/dart bin/run.dart -t bin/tasks/web_benchmarks_canvaskit.dart
```