commit	fd8240d38bad7c3577f20e358a81a36f76192ab3	[log] [tgz]
author	Primiano Tucci <primiano@google.com>	Wed Aug 01 09:34:54 2018 +0100
committer	Primiano Tucci <primiano@google.com>	Wed Aug 01 09:34:54 2018 +0100
tree	3208af018ccf0bea6a95332286a65ff59828c3d1
parent	a52306a4a7f2ae7966f8f1766c14cd850f62908f [diff]

Simplify ftrace architecture and integration with traced_probes

Historically the ftrace reader code has been strongly decoupled
from the rest of the codebase. The use case that was justifying
it (fall back into a library for other perf tools) is no more,
and we are left with extra layers that are unneeded and hurt
code readability. This CL removes the glue layers between
ftrace and probes_producer, in preparation of upcoming behavioral
changes (Flush). The main changes introduced by this CL are:
- Introduce a base class with hand-rolled RTTI for probes_producer.
  This simplifies the bookkeeping logic within the traced_probes
  binary.
- Collapse Ftrace's Sink and SinkDelegate into a FtraceDataSource
  class. FDS keeps track of all the state of ftrace for a given
  tracing session.
- Remove ftrace/end_to_end_integrationtest.cc, it had just two
  tests and they were disabled.
- Minor cleanups: introduce PERFETTO_WARN_UNUSED_RESULT; move
  stats to a dedicated header.

Change-Id: I7047fc07bbaf9f9bf862cdb81c87e567ffbc6779

33 files changed

tree: 3208af018ccf0bea6a95332286a65ff59828c3d1

README.md

Perfetto - Performance instrumentation and tracing

Perfetto is an open-source project for performance instrumentation and tracing of Linux/Android/Chrome platforms and user-space apps.
It consists of:

A portable, high efficiency, user-space tracing library
designed for tracing of multi-process systems, based on zero-alloc zero-copy zero-syscall (on fast-paths) writing of protobufs over shared memory.

OS-wide Linux/Android probes for platform debugging

Kernel tracing: a daemon that converts Kernel Ftrace events into API-stable protobufs, on device, with low overhead.
I/O tracing
Many new probes coming soon: heap profiling, perf sampling, syscall tracing.

Web-based frontend
A UI for inspection and analysis of traces (coming soon).

Batch processing of traces
A python / C++ (TBD) library for trace-based metrics (coming soon).

Perfetto Stack

Goals

Perfetto is building the next-gen unified tracing ecosystem for:

Android platform tracing (Systrace)
Chrome platform tracing (chrome://tracing)
App-defined user-space tracing (including support for non-Android apps).

The goal is to create an open, portable and developer friendly tracing ecosystem for app and platform performance debugging.

Key features

Designed for production
Perfetto's tracing library and daemons are designed for use in production. Privilege isolation is a key design goal:

The interface for writing trace events are decoupled from the interface for read-back and control and can be subjected to different ACLs.
Despite being based on shared memory, Perfetto is designed to prevent cross-talk between data sources, even in case of arbitrary code execution (memory is shared point-to-point, memory is never shared between processes).
Perfetto daemons are designed following to the principle of least privilege, in order to allow strong sandboxing (via SELinux on Android).

See docs/security-model.md for more details.

Long traces
Pefetto aims at supporting hours-long / O(100GB) traces, both in terms of recording backend and UI frontend.

Interoperability
Perfetto traces (output) and configuration (input) consists of protobuf messages, in order to allow interoperability with several languages.

See docs/trace-format.md for more details.

Composability
As Perfetto is designed both for OS-level tracing and app-level tracing, its design allows to compose several instances of the Perfetto tracing library, allowing to nest multiple layers of tracing and drive then with the same frontend. This allows powerful blending of app-specific and OS-wide trace events. See docs/multi-layer-tracing.md for more details.

Portability
The only dependencies of Perfetto's tracing libraries are C++11 and Protobuf lite (plus google-test, google-benchmark, libprotobuf-full for testing).

Extensibility
Perfetto allows third parties to defined their own protobufs for:

Allowing apps to define their own strongly-typed input and output schema. See docs/trace-format.md for more details.

Docs

Bugs

For bugs affecting Android or the tracing internals use the internal bug tracker (go/perfetto-bugs).
For bugs affecting Chrome use http://crbug.com, Component:Speed>Tracing label:Perfetto.