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: since LTTng-UST 2.3, both tracepoints and
 114     tracepoint probes can be compiled with g++.
 115
 116
 117 ENVIRONMENT VARIABLES:
 118
 119   - liblttng-ust debug can be activated by setting the environment variable
 120     "LTTNG_UST_DEBUG" when launching the application. It can also be enabled
 121     at compile-time by compiling libust with -DLTTNG_UST_DEBUG.
 122
 123   - The environment variable "LTTNG_UST_REGISTER_TIMEOUT" can be used to
 124     specify how long the applications should wait for sessiond
 125     "registration done" command before proceeding to execute the main
 126     program. The default is 3000ms (3 seconds). The timeout value is
 127     specified in milliseconds. The value 0 means "don't wait". The value
 128     -1 means "wait forever". Setting this environment variable to 0 is
 129     recommended for applications with time constraints on the process
 130     startup time.
 131
 132   - The compilation flag "-DLTTNG_UST_DEBUG_VALGRIND" should be enabled
 133     at build time to allow liblttng-ust to be used with valgrind
 134     (side-effect: disables per-cpu buffering).
 135
 136
 137 TRACE VIEWER:
 138
 139   Use babeltrace for viewing traces generated by LTTng UST 2.x.
 140   See http://lttng.org for download.
 141
 142
 143 CONTACT:
 144
 145   Maintainer: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 146   Mailing list: lttng-dev@lists.lttng.org
 147
 148
 149 PACKAGE CONTENTS:
 150
 151   This package contains the following elements.
 152
 153   - liblttng-ust
 154     The actual userspace tracing library that must be linked to the
 155     instrumented programs.
 156
 157   - include
 158     The public header files that will be installed on the system.
 159
 160   - tests
 161     Various test programs
 162
 163   - liblttng-ust-libc-wrapper
 164     An example library that can be LD_PRELOAD'ed to instrument some
 165     calls to libc (currently malloc() and free()) in any program without
 166     need to recompile it.
 167
 168   - liblttng-ust-fork
 169     A library that is LD_PRELOAD'ed, and that hijacks calls to several system
 170     calls in order to trace across these calls. It _has_ to be LD_PRELOAD'ed
 171     in order to hijack calls. In contrast, libust may be linked at build time.
 172
 173   - liblttng-ust-ctl
 174     A library to control tracing in other processes. Used by lttng-tools.
 175
 176   - liblttng-ust-comm
 177     A static library shared between libust and lttng-tools, that
 178     provides functions that allow these components to communicate together.
 179
 180   - libringbuffer
 181     The ring buffer implementation used within LTTng-UST.
 182
 183   - snprintf
 184     An asynchronous signal-safe version of snprintf.
 185
 186   - liblttng-ust-java
 187     A simple library that uses JNI to allow tracing in java programs.
 188     See liblttng-ust-java/README for build instructions.