contents/using-lttng/instrumenting/c-application/assigning-log-levels.md

   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 ~~~