Capture Macrobenchmark metrics

Metrics are the main type of information extracted from your benchmarks. They are passed to the measureRepeated function as a List, which lets you specify multiple measured metrics at once. At least one type of metric is required for the benchmark to run.

The following code snippet captures frame timing and custom trace section metrics.

benchmarkRule.measureRepeated(
    packageName = TARGET_PACKAGE,
    metrics = listOf(
        FrameTimingMetric(),
        TraceSectionMetric("RV CreateView"),
        TraceSectionMetric("RV OnBindView"),
    ),
    // ...
)

benchmarkRule.measureRepeated(
    /\* packageName \*/ TARGET_PACKAGE,
    /\* metrics \*/ Arrays.asList(
        new StartupTimingMetric(),
        new TraceSectionMetric("RV CreateView"),
        new TraceSectionMetric("RV OnBindView"),
    ),
    /\* iterations \*/ 5,
    // ...
);

Benchmark results are output to Android Studio, as shown in the following image. If multiple metrics are defined, all of them are combined in the output.

StartupTimingMetric

StartupTimingMetric captures app startup timing metrics with the following values:

• timeToInitialDisplayMs: The amount of time from when the system receives a launch intent to when it renders the first frame of the destination Activity.
• timeToFullDisplayMs: The amount of time from when the system receives a launch intent to when the application reports fully drawn using the reportFullyDrawn method. The measurement stops at the completion of rendering the first frame after—or containing—the reportFullyDrawn() call. This measurement might not be available on Android 10 (API level 29) and lower.

For more information about what contributes to application startup time, see App startup time.

Improve startup timing accuracy

The two key metrics for measuring app startup times are time to initial display (TTID) and time to full display (TTFD). TTID is the time it takes to display the first frame of the application UI. TTFD also includes the time to display any content that is loaded asynchronously after the initial frame is displayed.

TTFD is reported once the reportFullyDrawn() method of the ComponentActivity is called. If reportFullyDrawn() is never called, the TTID is reported instead. You might need to delay when reportFullyDrawn() is called until after the asynchronous loading is complete. For example, if the UI contains a dynamic list such as a RecyclerView or lazy list, this might be populated by a background task that completes after the list is first drawn and, therefore, after the UI is marked as fully drawn. In such cases, the list population isn't included in the benchmarking.

To include the list population as part of your benchmark timing, get the FullyDrawnReporter by using getFullyDrawnReporter() and add a reporter to it in your app code. You must release the reporter once the background task finishes populating the list. The FullyDrawnReporter doesn't call the reportFullyDrawn() method until all added reporters are released. By adding a recorder untilx the background process completes, the timings also include the amount of time it takes to populate the list in the startup timing data. This doesn't change the app's behavior for the user, but it lets the timing startup data include the time it takes to populate the list.

If your app uses Jetpack Compose, you can use the following APIs to indicate fully drawn state:

• ReportDrawn Indicates that your composable is immediately ready for interaction.
• ReportDrawnWhen takes a predicate, such as list.count > 0, to indicate when your composable is ready for interaction.
• ReportDrawnAfter Takes a suspending method that, when it completes, indicates that your composable is ready for interaction.

FrameTimingMetric

FrameTimingMetric captures timing information from frames produced by a benchmark, such as a scrolling or animation, and outputs the following values:

• frameOverrunMs: The amount of time a given frame misses its deadline by. Positive numbers indicate a dropped frame and visible jank or stutter. Negative numbers indicate how much faster a frame is than the deadline. Note: This is available only on Android 12 (API level 31) and higher.
• frameDurationCpuMs: The amount of time the frame takes to be produced on the CPU on both the UI thread and the RenderThread.

These measurements are collected in a distribution: 50th, 90th, 95th, and 99th percentile.

For more information about how to identify and improve slow frames, see Slow rendering.

TraceSectionMetric (experimental)

TraceSectionMetric captures the amount of time taken by a trace section matching the provided sectionName and outputs min, median, and maximum time in milliseconds. The trace section is defined either by the function call trace(sectionName) or the code between Trace.beginSection(sectionName) and Trace.endSection() or their async variants. It always selects the first instance of a trace section captured during a measurement.

For more information about tracing, see Overview of system tracing and Define custom events.

PowerMetric (experimental)

PowerMetric captures the change in power or energy over the duration of your test for the provided power categories. Each selected category is broken down into its measurable subcomponents, and unselected categories are added to the "unselected" metric. Metrics measure system-wide consumption, not the consumption on a per-app basis, and are limited to Pixel 6 and Pixel 6 Pro devices.

• power<category>Uw: The amount of power consumed over the duration of your test in this category.
• energy<category>Uws: The amount of energy transferred per unit of time for the duration of your test in this category.

Categories include the following:

• CPU
• DISPLAY
• GPU
• GPS
• MEMORY
• MACHINE_LEARNING
• NETWORK
• UNCATEGORIZED

With some categories, like CPU, it might be difficult to separate work done by other processes from work done by your own app. Minimize the interference by removing or restricting unnecessary apps and accounts.