[lttng-docs.git] / contents / using-lttng / intro.md

---
id: using-lttng
---

Using LTTng involves two main activities: **instrumenting** and
**controlling tracing**.

_[Instrumenting](#doc-instrumenting)_ is the process of inserting probes
into some source code. It can be done manually, by writing tracepoint
calls at specific locations in the source code of the program to trace,
or more automatically using dynamic probes (address in assembled code,
symbol name, function entry/return, etc.).

It has to be noted that, as an LTTng user, you may not have to worry
about the instrumentation process. Indeed, you may want to trace a
program already instrumented. As an example, the Linux kernel is
thoroughly instrumented, which is why you can trace it without caring
about adding probes.

_[Controlling tracing](#doc-controlling-tracing)_ is everything
that can be done by the LTTng session daemon, which is controlled using
`liblttng-ctl` or its command line utility, `lttng`: creating tracing
sessions, listing tracing sessions and events, enabling/disabling
events, starting/stopping the tracers, taking snapshots, etc.

This chapter is a complete user guide of both activities,
with common use cases of LTTng exposed throughout the text. It is
assumed that you are familiar with LTTng's concepts (events, channels,
domains, tracing sessions) and that you understand the roles of its
components (daemons, libraries, command line tools); if not, we invite
you to read the [Understanding LTTng](#doc-understanding-lttng) chapter
before you begin reading this one.

If you're new to LTTng, we suggest that you rather start with the
[Getting started](#doc-getting-started) small guide first, then come
back here to broaden your knowledge.

If you're only interested in tracing the Linux kernel with its current
instrumentation, you may skip the
[Instrumenting](#doc-instrumenting) section.
Commit	Line	Data
5e0cbfb0 PP	1	---
	2	id: using-lttng
	3	---
	4
	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, etc.).
	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, etc.
	25
	26	This chapter is a complete user guide of both activities,
	27	with common use cases of LTTng exposed throughout the text. It is
	28	assumed that you are familiar with LTTng's concepts (events, channels,
	29	domains, tracing sessions) and that you understand the roles of its
	30	components (daemons, libraries, command line tools); if not, we invite
	31	you to read the [Understanding LTTng](#doc-understanding-lttng) chapter
	32	before you begin reading this one.
	33
	34	If you're new to LTTng, we suggest that you rather start with the
	35	[Getting started](#doc-getting-started) small guide first, then come
	36	back here to broaden your knowledge.
	37
	38	If you're only interested in tracing the Linux kernel with its current
	39	instrumentation, you may skip the
	40	[Instrumenting](#doc-instrumenting) section.