From 6bb1cd1c9595413cdfd9a8875520e1c85e446833 Mon Sep 17 00:00:00 2001
From: Lukas Larsson <lukas@erlang-solutions.com>
Date: Wed, 23 May 2012 16:44:25 +0200
Subject: Move README and INSTALL to HOWTO folder

---
 HOWTO/SYSTEMTAP.md | 75 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 75 insertions(+)
 create mode 100644 HOWTO/SYSTEMTAP.md

(limited to 'HOWTO/SYSTEMTAP.md')

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