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v811_spc009/external/perfetto/docs/quickstart/linux-tracing.md

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Quickstart: Record traces on Linux

Perfetto can capture system traces on Linux. All ftrace-based data sources and most other procfs / sysfs-based data sources are supported.

Currently there are no packages or prebuilts for Linux. In order to run Perfetto on Linux you need to build it from source.

Building from source

  1. Check out the code:
git clone https://android.googlesource.com/platform/external/perfetto/ && cd perfetto
  1. Download and extract build dependencies:
tools/install-build-deps

If the script fails with SSL errors, try invoking it as python3 tools/install-build-deps, or upgrading your openssl libraries.

  1. Generate all most common GN build configurations:
tools/build_all_configs.py
  1. Build the Linux tracing binaries (On Linux it uses a hermetic clang toolchain, downloaded as part of step 2):
tools/ninja -C out/linux_clang_release traced traced_probes perfetto

This step is optional when using the convenience tools/tmux script below.

Capturing a trace

Due to Perfetto's service-based architecture, in order to capture a trace, the traced (session daemon) and traced_probes (probes and ftrace-interop daemon) need to be running.

For a quick start, the tools/tmux script takes care of building, setting up and running everything. As an example, let's look at the process scheduling data, which will be obtained from the Linux kernel via the ftrace interface.

  1. Run the convenience script with an example tracing config (10s duration):
OUT=out/linux_clang_release CONFIG=test/configs/scheduling.cfg tools/tmux -n

This will open a tmux window with three panes, one per the binary involved in tracing: traced, traced_probes and the perfetto client cmdline.

  1. Start the tracing session by running the pre-filled perfetto command in the down-most [consumer] pane.

  2. Detach from the tmux session with Ctrl-B D,or shut it down with tmux kill-session -t demo. The script will then copy the trace to /tmp/trace.protobuf, as a binary-encoded protobuf (see TracePacket reference).

Visualizing the trace

We can now explore the captured trace visually by using a dedicated web-based UI.

NOTE: The UI runs fully in-browser using JavaScript + Web Assembly. The trace file is not uploaded anywhere by default, unless you explicitly click on the 'Share' link.

  1. Navigate to ui.perfetto.dev in a browser.

  2. Click the Open trace file on the left-hand menu, and load the captured trace (by default at /tmp/trace.protobuf).

  3. Explore the trace by zooming/panning using WASD, and mouse for expanding process tracks (rows) into their constituent thread tracks. Press "?" for further navigation controls.

Alternatively, you can explore the trace contents issuing SQL queries through the trace processor.