Google Git
Sign in
fuchsia/third_party/github.com/google/perfetto/07870c112479c86ada6c5be11d43f4ee7978fca3
commit
07870c112479c86ada6c5be11d43f4ee7978fca3
[log]
author
Zimuzo Ezeozue <zezeozue@google.com>
Wed May 20 08:58:38 2026 +0000
committer
Zimuzo Ezeozue <zezeozue@google.com>
Wed May 20 18:12:05 2026 +0100
tree
6d0a24c686a218120e69ce3b94cc08ff7fb1d845
parent
02cfc2b9134d1a0b6b0dbaab9ac4ad5205335e2a [diff]
android_sdk: SDK low-level emit design document (README)

Rewrite the SDK README as a Perfetto-style design document. Walks through the
old HL-based Java path and the two C ABIs (HL and LL), the new mechanism (Java
encodes the TrackEvent body with protozero, native runs the LL loop), and how
an emitted packet reaches a trace buffer via the per-instance TraceWriter and
the shared memory buffer (the producer<->traced sharing is touched on but kept
out of scope).

Covers the emit buffers and the two body copies (heap byte[] -> off-heap
EmitBuffer -> SMB), why ProtoWriter encodes into a heap byte[], which copies
are avoidable vs fundamental (vs the C++ zero-copy-into-SMB), the off-heap
frame layout, the @CriticalNative call, the public API (tracks/timestamps/
typed proto fields/custom data sources), the migration CL stack, and the host
benchmark results with how-to-run and host-vs-device caveats.
1 file changed
tree: 6d0a24c686a218120e69ce3b94cc08ff7fb1d845
  1. .github/
  2. ai/
  3. bazel/
  4. build_overrides/
  5. buildtools/
  6. contrib/
  7. docs/
  8. examples/
  9. gn/
  10. include/
  11. infra/
  12. protos/
  13. python/
  14. sdk/
  15. src/
  16. test/
  17. third_party/
  18. tools/
  19. ui/
  20. CLAUDE.md ⇨ docs/AGENTS.md
  21. GEMINI.md ⇨ docs/AGENTS.md
  22. .bazelignore
  23. .bazelrc
  24. .bazelversion
  25. .clang-format
  26. .clang-tidy
  27. .git-blame-ignore-revs
  28. .gitallowed
  29. .gitattributes
  30. .gitignore
  31. .gn
  32. .style.yapf
  33. Android.bp
  34. Android.bp.extras
  35. BUILD
  36. BUILD.extras
  37. BUILD.gn
  38. CHANGELOG
  39. CONTRIBUTORS.txt
  40. DIR_METADATA
  41. heapprofd.rc
  42. LICENSE
  43. meson.build
  44. METADATA
  45. MODULE.bazel
  46. MODULE.bazel.lock
  47. MODULE_LICENSE_APACHE2
  48. OWNERS
  49. OWNERS.github
  50. perfetto.rc
  51. perfetto_flags.aconfig
  52. PerfettoIntegrationTests.xml
  53. persistent_cfg.pbtxt
  54. README.chromium
  55. README.md
  56. TEST_MAPPING
  57. traced_perf.rc
  58. WORKSPACE
README.md

Perfetto - System profiling, app tracing and trace analysis

Perfetto is an open-source suite of SDKs, daemons and tools which use tracing to help developers understand the behaviour of complex systems and root-cause functional and performance issues on client and embedded systems.

It is a production-grade tool that is the default tracing system for the Android operating system and the Chromium browser.

Core Components

Perfetto is not a single tool, but a collection of components that work together:

  • High-performance tracing daemons: For capturing tracing information from many processes on a single machine into a unified trace file.
  • Low-overhead tracing SDK: A C++17 library for direct userspace-to-userspace tracing of timings and state changes in your application.
  • Extensive OS-level probes: For capturing system-wide context on Android and Linux (e.g. scheduling states, CPU frequencies, memory profiling, callstack sampling).
  • Browser-based UI: A powerful, fully local UI for visualizing and exploring large, multi-GB traces on a timeline. It works in all major browsers, requires no installation, and can open traces from other tools.
  • SQL-based analysis library: A powerful engine that allows you to programmatically query traces using SQL to automate analysis and extract custom metrics.

Why Use Perfetto?

Perfetto was designed to be a versatile and powerful tracing system for a wide range of use cases.

  • For Android App & Platform Developers: Debug and root-cause functional and performance issues like slow startups, dropped frames (jank), animation glitches, low memory kills, and ANRs. Profile both Java/Kotlin and native C++ memory usage with heap dumps and profiles.
  • For C/C++ Developers (Linux, macOS, Windows): Use the Tracing SDK to instrument your application with custom trace points to understand its execution flow, find performance bottlenecks, and debug complex behavior. On Linux, you can also perform detailed CPU and native heap profiling.
  • For Linux Kernel & System Developers: Get deep insights into kernel behavior. Perfetto acts as an efficient userspace daemon for ftrace, allowing you to visualize scheduling, syscalls, interrupts, and custom kernel tracepoints on a timeline.
  • For Chromium Developers: Perfetto is the tracing backend for chrome://tracing. Use it to debug and root-cause issues in the browser, V8, and Blink.
  • For Performance Engineers & SREs: Analyze and visualize a wide range of profiling and tracing formats, not just Perfetto's. Use the powerful SQL interface to programmatically analyze traces from tools like Linux perf, macOS Instruments, Chrome JSON traces, and more.

Getting Started

We‘ve designed our documentation to guide you to the right information as quickly as possible, whether you’re a newcomer to performance analysis or an experienced developer.

  1. New to tracing? If you're unfamiliar with concepts like tracing and profiling, start here:

  2. Ready to dive in? Our “Getting Started” guide is the main entry point for all users. It will help you find the right tutorials and documentation for your specific needs:

  3. Want the full overview? For a comprehensive look at what Perfetto is, why it's useful, and who uses it, see our main documentation page:

Debian Distribution

For users interested in the Debian distribution of Perfetto, the official source of truth and packaging efforts are maintained at Debian Perfetto Salsa Repository

Community & Support

Have questions? Need help?

We follow Google's Open Source Community Guidelines.