Documentation/rtla: Mention default priority

RTLA allows the priority of workload threads to be set using the -P
option. This is covered in docs, but the default state for RTLA's own
user workload (implemented in timerlat_u.c) is not mentioned.

Add mention of the default user workload priority as well as a reference
to osnoise and timerlat tracers for kernel workload priority.

Signed-off-by: Tomas Glozar <tglozar@redhat.com>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Message-ID: <20251010083338.478961-7-tglozar@redhat.com>

diff --git a/Documentation/tools/rtla/common_options.txt b/Documentation/tools/rtla/common_options.txt
index a2f9c03810b90e7b23faaa8a1570b8590d1ec601..b842f065c8f68202c3eb9e64f9aa453fa1b29018 100644 (file)
--- a/Documentation/tools/rtla/common_options.txt
+++ b/Documentation/tools/rtla/common_options.txt
@@ -42,6 +42,8 @@
         - *f:prio* - use SCHED_FIFO with *prio*;
         - *d:runtime[us|ms|s]:period[us|ms|s]* - use SCHED_DEADLINE with *runtime* and *period* in nanoseconds.
 
+        If not set, tracer threads keep their default priority. For rtla user threads, it is set to SCHED_FIFO with priority 95. For kernel threads, see *osnoise* and *timerlat* tracer documentation for the running kernel version.
+
 **-C**, **--cgroup**\[*=cgroup*]
 
         Set a *cgroup* to the tracer's threads. If the **-C** option is passed without arguments, the tracer's thread will inherit **rtla**'s *cgroup*. Otherwise, the threads will be placed on the *cgroup* passed to the option.