perfetto - capture traces
This section describes how to use the perfetto commandline binary to capture traces. Examples are given in terms of an Android device connected over ADB.
perfetto has two modes for configuring the tracing session (i.e. what and how to collect):
lightweight mode : all config options are supplied as commandline flags, but the available data sources are restricted to ftrace and atrace. This mode is similar to systrace.
normal mode : the configuration is specified in a protocol buffer. This allows for full customisation of collected traces.
The following table lists the available options when using perfetto in either mode.
-d, --background : Perfetto immediately exits the command-line interface and continues recording your trace in background.
-o, --out OUT_FILE : Specifies the desired path to the output trace file, or - for stdout. perfetto writes the output to the file described in the flags above. The output format compiles with the format defined in AOSP trace.proto.
--dropbox TAG : Uploads your trace via the DropBoxManager API using the tag you specify. Android only.
--no-guardrails : Disables protections against excessive resource usage when enabling the --dropbox flag during testing.
--reset-guardrails : Resets the persistent state of the guardrails and exits (for testing).
--query : Queries the service state and prints it as human-readable text.
--query-raw : Similar to --query, but prints raw proto-encoded bytes of tracing_service_state.proto.
-h, --help : Prints out help text for the perfetto tool.
For ease of use, the perfetto command includes support for a subset of configurations via command line arguments. On-device, these configurations behave equivalently to the same configurations provided by a CONFIG_FILE (see below).
The general syntax for using perfetto in simple mode is as follows:
adb shell perfetto [ --time TIMESPEC ] [ --buffer SIZE ] [ --size SIZE ]
[ ATRACE_CAT | FTRACE_GROUP/FTRACE_NAME]...
The following table lists the available options when using perfetto in simple mode.
-t, --time TIME[s|m|h] : Specifies the trace duration in seconds, minutes, or hours. For example, --time 1m specifies a trace duration of 1 minute. The default duration is 10 seconds.
-b, --buffer SIZE[mb|gb] : Specifies the ring buffer size in megabytes (mb) or gigabytes (gb). The default parameter is --buffer 32mb.
-s, --size SIZE[mb|gb] : Specifies the max file size in megabytes (mb) or gigabytes (gb). By default perfetto uses only in-memory ring-buffer.
This is followed by a list of event specifiers:
ATRACE_CAT : Specifies the atrace categories you want to record a trace for. For example, the following command traces Window Manager using atrace: adb shell perfetto --out FILE wm. To record other categories, see the list of atrace categories. Note: Available categories are Android version dependent.
FTRACE_GROUP/FTRACE_NAME : Specifies the ftrace events you want to record a trace for. For example, the following command traces sched/sched_switch events: adb shell perfetto --out FILE sched/sched_switch
The general syntax for using perfetto in normal mode is as follows:
adb shell perfetto [ --txt ] --config CONFIG_FILE
The following table lists the available options when using perfetto in normal mode.
-c, --config CONFIG_FILE : Specifies the path to a configuration file. In normal mode, some configurations may be encoded in a configuration protocol buffer. This file must comply with the protocol buffer schema defined in AOSP trace_config.proto. You select and configure the data sources using the DataSourceConfig member of the TraceConfig, as defined in AOSP data_source_config.proto.
--txt : Instructs perfetto to parse the config file as pbtxt. This flag is experimental, and it's not recommended that you enable it for production.