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diff --git a/README.systemtap.md b/README.systemtap.md new file mode 100644 index 0000000000..3bb3e626cd --- /dev/null +++ b/README.systemtap.md @@ -0,0 +1,72 @@ +SystemTap and Erlang/OTP +======================== + +Introduction +------------ + +SystemTap is DTrace for Linux. In fact Erlang's SystemTap support +is build using SystemTap's DTrace compatibility's layer. For an +introduction to Erlang DTrace support read README.dtrace.md. + +Requisites +---------- + +* Linux Kernel with UTRACE support + + check for UTRACE support in your current kernel: + + # grep CONFIG_UTRACE /boot/config-`uname -r` + CONFIG_UTRACE=y + + Fedora 16 is known to contain UTRACE, for most other Linux distributions + a custom build kernel will be required. + Check Fedora's SystemTap documentation for additional required packages + (e.g. Kernel Debug Symbols) + +* SystemTap > 1.6 + + A the time of writing this, the latest released version of SystemTap is + version 1.6. Erlang's DTrace support requires a MACRO that was introduced + after that release. So either get a newer release or build SystemTap from + git yourself (see: http://sourceware.org/systemtap/getinvolved.html) + +Building Erlang +--------------- + +Configure and build Erlang with SystemTap support: + + # ./configure --enable-dtrace + whatever args you need + # make + +Testing +------- + +SystemTap, unlike DTrace, needs to know what binary it is tracing and has to +be able to read that binary before it starts tracing. Your probe script +therefor has to reference the correct beam emulator and stap needs to be able +to find that binary. +The examples are written for "beam", but other versions such as "beam.smp" or +"beam.debug.smp" might exist (depending on your configuration). Make sure you +either specify the full the path of the binary in the probe or your "beam" +binary is in the search path. + +All available probes can be listed like this: + + # stap -L 'process("beam").mark("*")' + +or: + + # PATH=/path/to/beam:$PATH stap -L 'process("beam").mark("*")' + + +Probes in the dtrace.so NIF library like this: + + # PATH=/path/to/dtrace/priv/lib:$PATH stap -L 'process("dtrace.so").mark("*")' + +Running SystemTap scripts +------------------------- + +Adjust the process("beam") reference to your beam version and attach the script +to a running "beam" instance: + + # stap /path/to/probe/script/port1.systemtap -x <pid of beam> |