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:
Kotlin
benchmarkRule.measureRepeated(
packageName = TARGET_PACKAGE,
metrics = listOf(
FrameTimingMetric(),
TraceSectionMetric("RV CreateView"),
TraceSectionMetric("RV OnBindView"),
),
iterations = 5,
// ...
)
Java
benchmarkRule.measureRepeated(
TARGET_PACKAGE, // packageName
Arrays.asList(
// metrics
new StartupTimingMetric(),
new TraceSectionMetric("RV CreateView"),
new TraceSectionMetric("RV OnBindView"),
),
5, // Iterations
// ...
);
In this example,
RV CreateView
and
RV OnBindView
are the IDs of traceable blocks that are defined in
RecyclerView
. The
source code for the
createViewHolder()
method is an example of how you can define traceable blocks within your own
code.
StartupTimingMetric
,
TraceSectionMetric
,
FrameTimingMetric
, and
PowerMetric
, are covered
in detail later in this document.
Benchmark results are output to Android Studio, as shown in figure 1.
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 app 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 earlier.
StartupTimingMetric
outputs the min, median, and max values from the startup
iterations. To assess startup improvement you should focus on median values,
since they provide the best estimate of the typical startup time. For more
information about what contributes to app startup time, see
App startup
time
.
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 of 50th, 90th, 95th, and 99th
percentile.
For more information on how to identify and improve slow frames, see
Slow rendering
.
TraceSectionMetric
TraceSectionMetric
captures the number of times a trace section matching the provided
sectionName
occurs and the amount of time it takes. For the time, it outputs the minimum,
median, and maximum times 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. It only outputs trace sections from your package
by default; to include processes outside your package, set
targetPackageOnly = false
.
For more information about tracing, see
Overview of system
tracing
and
Define custom
events
.
PowerMetric
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.
These metrics measure
system-wide consumption, not the consumption on a per-app basis, and are limited
to Pixel 6, Pixel 6 Pro, and later 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. To minimize the interference,
remove or restrict unnecessary apps and accounts.
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