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flutter/third_party/perfetto/refs/heads/dev/jules/2461-counter-y-axis-linking
commit
c2c013dc4fb57afcc2dd1b81d79ee316c93dfdbe
[log]
author
google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>
Fri Aug 08 11:22:25 2025 +0000
committer
google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>
Fri Aug 08 11:22:25 2025 +0000
tree
7c093654413678deba5eb8d1de9748fa7849221e
parent
98b671f9c7c38d9711ac31700e7191a14db15c01 [diff]
Add support for linking counter y-axis with TrackEvent

This change adds support for linking the y-axis of counter tracks in the Perfetto UI. This is useful when multiple counter tracks are related and should be displayed with the same y-axis range for easier comparison.

The changes include:
- Adding a `y_axis_share_key` field to the `CounterDescriptor` proto.
- Propagating this key through the trace processor and adding it as a track argument.
- Updating the UI to use this key to group tracks for y-axis sharing. The parent track ID is also included in the sharing key to ensure that only tracks under the same parent are linked.
- Adding a diff test to verify the new feature.
- Updating the documentation.

Fixes #2461
10 files changed
tree: 7c093654413678deba5eb8d1de9748fa7849221e
  1. .github/
  2. bazel/
  3. build_overrides/
  4. buildtools/
  5. debian/
  6. docs/
  7. examples/
  8. gn/
  9. include/
  10. infra/
  11. protos/
  12. python/
  13. src/
  14. test/
  15. third_party/
  16. tools/
  17. ui/
  18. .bazelignore
  19. .bazelrc
  20. .bazelversion
  21. .clang-format
  22. .clang-tidy
  23. .git-blame-ignore-revs
  24. .gitallowed
  25. .gitattributes
  26. .gitignore
  27. .gn
  28. .style.yapf
  29. Android.bp
  30. Android.bp.extras
  31. BUILD
  32. BUILD.extras
  33. BUILD.gn
  34. CHANGELOG
  35. codereview.settings
  36. CONTRIBUTORS.txt
  37. DIR_METADATA
  38. heapprofd.rc
  39. LICENSE
  40. meson.build
  41. METADATA
  42. MODULE.bazel
  43. MODULE.bazel.lock
  44. MODULE_LICENSE_APACHE2
  45. OWNERS
  46. perfetto.rc
  47. perfetto_flags.aconfig
  48. PerfettoIntegrationTests.xml
  49. persistent_cfg.pbtxt
  50. README.chromium
  51. README.md
  52. TEST_MAPPING
  53. traced_perf.rc
  54. WATCHLISTS
  55. 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:

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