[lttng-docs.git] / contents / using-lttng / instrumenting / c-application / assigning-log-levels.md

---
id: assigning-log-levels
---

Optionally, a log level can be assigned to a defined tracepoint.
Assigning different levels of importance to tracepoints can be useful;
when controlling tracing sessions,
[you can choose](#doc-controlling-tracing) to only enable tracepoints
falling into a specific log level range.

Log levels are assigned to defined tracepoints using the
`TRACEPOINT_LOGLEVEL()` macro. The latter must be used _after_ having
used `TRACEPOINT_EVENT()` for a given tracepoint. The
`TRACEPOINT_LOGLEVEL()` macro has the following construct:

~~~ c
TRACEPOINT_LOGLEVEL(<provider name>, <tracepoint name>, <log level>)
~~~

where the first two arguments are the same as the first two arguments
of `TRACEPOINT_EVENT()` and `<log level>` is one
of the values given in the
[LTTng-UST library reference](#doc-liblttng-ust-tracepoint-loglevel)
section.

As an example, let's assign a `TRACE_DEBUG_UNIT` log level to our
previous tracepoint definition:

~~~ c
TRACEPOINT_LOGLEVEL(my_provider, my_tracepoint, TRACE_DEBUG_UNIT)
~~~
Commit	Line	Data
5e0cbfb0 PP	1	---
	2	id: assigning-log-levels
	3	---
	4
	5	Optionally, a log level can be assigned to a defined tracepoint.
	6	Assigning different levels of importance to tracepoints can be useful;
	7	when controlling tracing sessions,
	8	[you can choose](#doc-controlling-tracing) to only enable tracepoints
	9	falling into a specific log level range.
	10
	11	Log levels are assigned to defined tracepoints using the
	12	`TRACEPOINT_LOGLEVEL()` macro. The latter must be used _after_ having
	13	used `TRACEPOINT_EVENT()` for a given tracepoint. The
	14	`TRACEPOINT_LOGLEVEL()` macro has the following construct:
	15
	16	~~~ c
	17	TRACEPOINT_LOGLEVEL(<provider name>, <tracepoint name>, <log level>)
	18	~~~
	19
	20	where the first two arguments are the same as the first two arguments
	21	of `TRACEPOINT_EVENT()` and `<log level>` is one
	22	of the values given in the
	23	[LTTng-UST library reference](#doc-liblttng-ust-tracepoint-loglevel)
	24	section.
	25
	26	As an example, let's assign a `TRACE_DEBUG_UNIT` log level to our
	27	previous tracepoint definition:
	28
	29	~~~ c
	30	TRACEPOINT_LOGLEVEL(my_provider, my_tracepoint, TRACE_DEBUG_UNIT)
	31	~~~