bcc README

The project's README from github.com/iovisor/bcc. As one markdown file: README.md.

BCC Logo

BPF Compiler Collection (BCC)

BCC is a toolkit for creating efficient kernel tracing and manipulation programs, and includes several useful tools and examples. It makes use of extended BPF (Berkeley Packet Filters), formally known as eBPF, a new feature that was first added to Linux 3.15. Much of what BCC uses requires Linux 4.1 and above.

eBPF was described by Ingo Molnár as:

One of the more interesting features in this cycle is the ability to attach eBPF programs (user-defined, sandboxed bytecode executed by the kernel) to kprobes. This allows user-defined instrumentation on a live kernel image that can never crash, hang or interfere with the kernel negatively.

BCC makes BPF programs easier to write, with kernel instrumentation in C (and includes a C wrapper around LLVM), and front-ends in Python and lua. It is suited for many tasks, including performance analysis and network traffic control.

Screenshot

This example traces a disk I/O kernel function, and populates an in-kernel power-of-2 histogram of the I/O size. For efficiency, only the histogram summary is returned to user-level.

# ./bitehist.py
Tracing... Hit Ctrl-C to end.
^C
     kbytes          : count     distribution
       0 -> 1        : 3        |                                      |
       2 -> 3        : 0        |                                      |
       4 -> 7        : 211      |**********                            |
       8 -> 15       : 0        |                                      |
      16 -> 31       : 0        |                                      |
      32 -> 63       : 0        |                                      |
      64 -> 127      : 1        |                                      |
     128 -> 255      : 800      |**************************************|

The above output shows a bimodal distribution, where the largest mode of 800 I/O was between 128 and 255 Kbytes in size.

See the source: bitehist.py. What this traces, what this stores, and how the data is presented, can be entirely customized. This shows only some of many possible capabilities.

Installing

See INSTALL.md for installation steps on your platform.

FAQ

See FAQ.txt for the most common troubleshoot questions.

Reference guide

See docs/reference_guide.md for the reference guide to the bcc and bcc/BPF APIs.

Contents

Some of these are single files that contain both C and Python, others have a pair of .c and .py files, and some are directories of files.

Tracing

Examples

Tools

Memory and Process Tools
Performance and Time Tools
CPU and Scheduler Tools
Network and Sockets Tools
Storage and Filesystems Tools
Filesystems Tools

Networking

Examples:

BPF Introspection

Tools that help to introspect BPF programs.

Motivation

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:

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!

Tutorials

Networking

At Red Hat Summit 2015, BCC was presented as part of a session on BPF. A multi-host vxlan environment is simulated and a BPF program used to monitor one of the physical interfaces. The BPF program keeps statistics on the inner and outer IP addresses traversing the interface, and the userspace component turns those statistics into a graph showing the traffic distribution at multiple granularities. See the code here.

Contributing

Already pumped up to commit some code? Here are some resources to join the discussions in the IOVisor community and see what you want to work on.

Looking for more information on BCC and how it's being used? You can find links to other BCC content on the web in LINKS.md.

bcc (iovisor/bcc)

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22.7K ·GitHub
Bcc
What is this?BCC (BPF Compiler Collection) is a toolkit for creating efficient kernel tracing and manipulation programs on Linux using eBPF. It also ships a large collection of ready-made tools for I/O analysis, networking, and monitoring.
Is it a framework for writing my own tracers, or a set of tools I just run?Both. You write kernel instrumentation in C (via a C wrapper around LLVM) with Python or Lua front-ends — and the repo also includes dozens of standalone tools like opensnoop, biolatency, and tcptop you can run as-is.
Does my kernel need to be a certain version?Yes — it is Linux-only by nature: eBPF first appeared in Linux 3.15, and much of what BCC uses requires Linux 4.1 and above, so a reasonably recent kernel matters.
Is it safe to attach this to a running kernel?That is the core promise of eBPF: programs are user-defined, sandboxed bytecode executed by the kernel — instrumentation on a live kernel image that can never crash, hang, or interfere with the kernel negatively.
What can I actually do with the bundled tools?Day-to-day stuff like execsnoop (new processes), opensnoop (file opens), biolatency (disk I/O latency histograms), profile (CPU sampling), offcputime, memleak (leak hunting), tcpconnect and tcptop (TCP), plus dbslower for slow MySQL/PostgreSQL queries.
Do I have to write C code to build my own tracer?Not for the bundled tools. For custom ones, the kernel part is written in C and driven from a Python or Lua front-end; the examples come either as single files mixing C and Python or as .c/.py pairs.
Can it do more than observe, like controlling network traffic?Yes. Besides tracing, the README names network traffic control as a key use, with examples such as an HTTP filter, a distributed bridge, and per-IP classification with rate limiting.
Which app runtimes can it trace inside?MySQL and Node.js via USDT probes, plus a family of high-level-language tools — ucalls, uflow, ugc, ustat, uthreads — that summarize method calls, GC events, object allocations, exceptions, and thread creation in runtimes like Java.
What are similar projects?perf-tools, bpftrace, scalene, android-internals-wiki, ecapture, cilium, zfs, linux
Which topics is it in?ebpf, profiling, linux-kernel, kernel, lua, systems-programming, debugging, sysadmin, observability, c, monitoring, networking
Creator
iovisor
Size
23.4 MB
Stars
22.7K
Updated
CommitOct 02Releasev0.37.0Jul 02
Age
11y
Commits · 90 Days