This directory contains Lua tooling for BCC (the BPF Compiler Collection).

BCC is a toolkit for creating userspace and kernel tracing programs. By default, it comes with a library libbcc, some example tooling and a Python frontend for the library.

Here we present an alternate frontend for libbcc implemented in LuaJIT. This lets you write the userspace part of your tracer in Lua instead of Python.

Since LuaJIT is a JIT compiled language, tracers implemented in bcc-lua exhibit significantly reduced overhead compared to their Python equivalents. This is particularly noticeable in tracers that actively use the table APIs to get information from the kernel.

If your tracer makes extensive use of BPF_MAP_TYPE_PERF_EVENT_ARRAY or BPF_MAP_TYPE_HASH, you may find the performance characteristics of this implementation very appealing, as LuaJIT can compile to native code a lot of the callchain to process the events, and this wrapper has been designed to benefit from such JIT compilation.

The following instructions assume Ubuntu 14.04 LTS.

1. Install a very new kernel. It has to be new and shiny for this to work. 4.3+

   VER=4.4.2-040402
   PREFIX=http:https://kernel.ubuntu.com/~kernel-ppa/mainline/v4.4.2-wily/
   REL=201602171633
   wget ${PREFIX}/linux-headers-${VER}-generic_${VER}.${REL}_amd64.deb
   wget ${PREFIX}/linux-headers-${VER}_${VER}.${REL}_all.deb
   wget ${PREFIX}/linux-image-${VER}-generic_${VER}.${REL}_amd64.deb
   sudo dpkg -i linux-*${VER}.${REL}*.deb
   

2. Install the libbcc binary packages and luajit

   sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys D4284CDD
   echo "deb http:https://52.8.15.63/apt trusty main" | sudo tee /etc/apt/sources.list.d/iovisor.list
   sudo apt-get update
   sudo apt-get install libbcc luajit
   

3. Test one of the examples to ensure libbcc is properly installed

   sudo ./bcc-probe examples/lua/task_switch.lua