README

   1 LTTNG USERSPACE TRACER (LTTng-UST)
   2 ----------------------------
   3
   4 UST web site: http://lttng.org
   5
   6 Updated versions of this package may be found at:
   7
   8   * Releases: http://lttng.org/download
   9   * GitWeb:   http://git.lttng.org (project: lttng-ust)
  10   * Git:      git://git.lttng.org/lttng-ust.git
  11
  12
  13 PREREQUISITES:
  14
  15   - liburcu
  16     Userspace RCU library, by Mathieu Desnoyers and Paul E. McKenney
  17
  18     -> This release depends on liburcu v0.7.2
  19
  20       * Debian/Ubuntu package: liburcu-dev
  21       * Website:  http://lttng.org/urcu
  22       * Releases: http://lttng.org/files/urcu
  23       * GitWeb:   http://lttng.org/cgi-bin/gitweb.cgi?p=userspace-rcu.git;a=summary
  24       * Git:      git://lttng.org/userspace-rcu.git
  25
  26 For developers using the git tree:
  27
  28 This source tree is based on the autotools suite from GNU to simplify
  29 portability. Here are some things you should have on your system in order to
  30 compile the git repository tree :
  31
  32 - GNU autotools (automake >=1.10, autoconf >=2.50, autoheader >=2.50)
  33   (make sure your system wide "automake" points to a recent version!)
  34 - GNU Libtool >=2.2
  35   (for more information, go to http://www.gnu.org/software/autoconf/)
  36 - Perl (optional)
  37   Needed for make check and tests.
  38
  39 If you get the tree from the repository, you will need to use the "bootstrap"
  40 script in the root of the tree. It calls all the GNU tools needed to prepare the
  41 tree configuration.
  42
  43
  44 INSTALLATION INSTRUCTIONS:
  45
  46   - Download, compile and install liburcu.
  47   - In this package's tree, run ./configure.
  48   - Run make.
  49   - Run make install.
  50   - Run ldconfig.
  51
  52   If compiling from the git repository, run ./bootstrap before running
  53   the configure script, to generate it.
  54
  55   Note that configure sets '/usr/local' as the default prefix for files it
  56   installs. However, this path is not part of most distributions' default
  57   library path which will cause builds depending on liblttng-ust to fail unless
  58   '-L/usr/local/lib' is added to LDFLAGS. You may provide a custom prefix to
  59   configure by using the --prefix switch.
  60
  61 USAGE:
  62
  63   - Create an instrumentation header following the tracepoint examples.
  64     See lttng/tracepoint.h, and examples.
  65
  66   There are 2 ways to compile the Tracepoint Provider with the
  67   application: either statically or dynamically. Please follow
  68   carefully:
  69
  70   1.1) Compile the Tracepoint provider with the application, either
  71        directly or through a static library (.a):
  72     - Into exactly one object of your application: define
  73       "TRACEPOINT_DEFINE" and include the tracepoint provider.
  74     - Use "-I." for the compilation unit containing the tracepoint
  75       provider include (e.g. tp.c).
  76     - Link application with "-ldl" on Linux, with "-lc" on BSD.
  77     - If building the provider directly into the application,
  78       link the application with "-llttng-ust".
  79     - If building a static library for the provider, link the static
  80       library with "-llttng-ust".
  81     - Include the tracepoint provider header into all C files using
  82       the provider.
  83     - Examples:
  84       - doc/examples/easy-ust/   sample.c sample_component_provider.h
  85         tp.c Makefile
  86       - doc/examples/hello-static-lib/   hello.c tp.c ust_test_hello.h
  87         Makefile
  88
  89   2) Compile the Tracepoint Provider separately from the application,
  90      using dynamic linking:
  91     - Into exactly one object of your application: define
  92       "TRACEPOINT_DEFINE" _and_ also define
  93       "TRACEPOINT_PROBE_DYNAMIC_LINKAGE", then include the tracepoint
  94       provider header.
  95     - Include the tracepoint provider header into all instrumented C
  96       files that use the provider.
  97     - Compile the tracepoint provider with "-I.".
  98     - Link the tracepoint provider with "-llttng-ust".
  99     - Link application with "-ldl" on Linux, "-lc" on BSD.
 100     - Set a LD_PRELOAD environment to preload the tracepoint provider
 101       shared object before starting the application when tracing is
 102       needed. Another way is to dlopen the tracepoint probe when needed
 103       by the application.
 104     - Example:
 105       - doc/examples/demo   demo.c  tp*.c ust_tests_demo*.h demo-trace Makefile
 106
 107   - Note about dlclose() usage: it is not safe to use dlclose on a
 108     provider shared object that is being actively used for tracing due
 109     to a lack of reference counting from lttng-ust to the used shared
 110     object.
 111   - Enable instrumentation and control tracing with the "lttng" command
 112     from lttng-tools. See lttng-tools doc/quickstart.txt.
 113   - Note for C++ support: although an application instrumented with
 114     tracepoints can be compiled with g++, tracepoint probes should be
 115     compiled with gcc (only tested with gcc so far).
 116
 117
 118 ENVIRONMENT VARIABLES:
 119
 120   - liblttng-ust debug can be activated by setting the environment variable
 121     "LTTNG_UST_DEBUG" when launching the application. It can also be enabled
 122     at compile-time by compiling libust with -DLTTNG_UST_DEBUG.
 123
 124   - The environment variable "LTTNG_UST_REGISTER_TIMEOUT" can be used to
 125     specify how long the applications should wait for sessiond
 126     "registration done" command before proceeding to execute the main
 127     program. The default is 3000ms (3 seconds). The timeout value is
 128     specified in milliseconds. The value 0 means "don't wait". The value
 129     -1 means "wait forever". Setting this environment variable to 0 is
 130     recommended for applications with time constraints on the process
 131     startup time.
 132
 133   - The compilation flag "-DLTTNG_UST_DEBUG_VALGRIND" should be enabled
 134     at build time to allow liblttng-ust to be used with valgrind
 135     (side-effect: disables per-cpu buffering).
 136
 137
 138 TRACE VIEWER:
 139
 140   Use babeltrace for viewing traces generated by LTTng UST 2.x.
 141   See http://lttng.org for download.
 142
 143
 144 CONTACT:
 145
 146   Maintainer: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 147   Mailing list: lttng-dev@lists.lttng.org
 148
 149
 150 PACKAGE CONTENTS:
 151
 152   This package contains the following elements.
 153
 154   - liblttng-ust
 155     The actual userspace tracing library that must be linked to the
 156     instrumented programs.
 157
 158   - include
 159     The public header files that will be installed on the system.
 160
 161   - tests
 162     Various test programs
 163
 164   - liblttng-ust-libc-wrapper
 165     An example library that can be LD_PRELOAD'ed to instrument some
 166     calls to libc (currently malloc() and free()) in any program without
 167     need to recompile it.
 168
 169   - liblttng-ust-fork
 170     A library that is LD_PRELOAD'ed, and that hijacks calls to several system
 171     calls in order to trace across these calls. It _has_ to be LD_PRELOAD'ed
 172     in order to hijack calls. In contrast, libust may be linked at build time.
 173
 174   - liblttng-ust-ctl
 175     A library to control tracing in other processes. Used by lttng-tools.
 176
 177   - liblttng-ust-comm
 178     A static library shared between libust and lttng-tools, that
 179     provides functions that allow these components to communicate together.
 180
 181   - libringbuffer
 182     The ring buffer implementation used within LTTng-UST.
 183
 184   - snprintf
 185     An asynchronous signal-safe version of snprintf.
 186
 187   - liblttng-ust-java
 188     A simple library that uses JNI to allow tracing in java programs.
 189     See liblttng-ust-java/README for build instructions.