contents/using-lttng/intro.md

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   2 id: using-lttng
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   5 Using LTTng involves two main activities: **instrumenting** and
   6 **controlling tracing**.
   7
   8 _[Instrumenting](#doc-instrumenting)_ is the process of inserting probes
   9 into some source code. It can be done manually, by writing tracepoint
  10 calls at specific locations in the source code of the program to trace,
  11 or more automatically using dynamic probes (address in assembled code,
  12 symbol name, function entry/return, and others).
  13
  14 It has to be noted that, as an LTTng user, you may not have to worry
  15 about the instrumentation process. Indeed, you may want to trace a
  16 program already instrumented. As an example, the Linux kernel is
  17 thoroughly instrumented, which is why you can trace it without caring
  18 about adding probes.
  19
  20 _[Controlling tracing](#doc-controlling-tracing)_ is everything
  21 that can be done by the LTTng session daemon, which is controlled using
  22 `liblttng-ctl` or its command line utility, `lttng`: creating tracing
  23 sessions, listing tracing sessions and events, enabling/disabling
  24 events, starting/stopping the tracers, taking snapshots, amongst many
  25 other commands.
  26
  27 This chapter is a complete user guide of both activities,
  28 with common use cases of LTTng exposed throughout the text. It is
  29 assumed that you are familiar with LTTng's concepts (events, channels,
  30 domains, tracing sessions) and that you understand the roles of its
  31 components (daemons, libraries, command line tools); if not, we invite
  32 you to read the [Understanding LTTng](#doc-understanding-lttng) chapter
  33 before you begin reading this one.
  34
  35 If you're new to LTTng, we suggest that you rather start with the
  36 [Getting started](#doc-getting-started) small guide first, then come
  37 back here to broaden your knowledge.
  38
  39 If you're only interested in tracing the Linux kernel with its current
  40 instrumentation, you may skip the
  41 [Instrumenting](#doc-instrumenting) section.