Published on April 13th, 2016 📆 | 7545 Views ⚑0
BCC — Dynamic Tracing Tools for Linux
BCC – BPF Compiler Collection – is a toolkit for creating efficient kernel tracing and manipulation programs, and includes several useful tools and examples. It makes use of eBPF (Extended Berkeley Packet Filters), a new feature that was first added to Linux 3.15. Much of what BCC uses requires Linux 4.1 and above. BCC makes eBPF programs easier to write, with kernel instrumentation in C and a front-end in Python. It is suited for many tasks, including performance analysis and network traffic control.
BPF guarantees that the programs loaded into the kernel cannot crash, and cannot run forever, but yet BPF is general purpose enough to perform many arbitrary types of computation. Currently, it is possible to write a program in C that will compile into a valid BPF program, yet it is vastly easier to write a C program that will compile into invalid BPF (C is like that). The user won’t know until trying to run the program whether it was valid or not.
With a BPF-specific frontend, one should be able to write in a language and receive feedback from the compiler on the validity as it pertains to a BPF backend. This toolkit aims to provide a frontend that can only create valid BPF programs while still harnessing its full flexibility.
Furthermore, current integrations with BPF have a kludgy workflow, sometimes involving compiling directly in a linux kernel source tree. This toolchain aims to minimize the time that a developer spends getting BPF compiled, and instead focus on the applications that can be written and the problems that can be solved with BPF.
The features of this toolkit include:
- End-to-end BPF workflow in a shared library
- A modified C language for BPF backends
- Integration with llvm-bpf backend for JIT
- Dynamic (un)loading of JITed programs
- Support for BPF kernel hooks: socket filters, tc classifiers, tc actions, and kprobes
- Bindings for Python
- Examples for socket filters, tc classifiers, and kprobes
- Self-contained tools for tracing a running system
In the future, more bindings besides python will likely be supported. Feel free to add support for the language of your choice and send a pull request!
Dynamic Tracing Tools for Linux
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