[PATCH 4/4] Documentation/osnoise: Add osnoise/options documentation

[Daniel Bristot de Oliveira <bristot@kernel.org>]

Add the documentation about the osnoise/options file, along
with an explanation about the OSNOISE_WORKLOAD option.

Cc: Daniel Bristot de Oliveira <bristot@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
---
 Documentation/trace/osnoise-tracer.rst | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/Documentation/trace/osnoise-tracer.rst b/Documentation/trace/osnoise-tracer.rst
index 963def9f97c6..e1eed255a4ac 100644
--- a/Documentation/trace/osnoise-tracer.rst
+++ b/Documentation/trace/osnoise-tracer.rst
@@ -109,6 +109,11 @@ The tracer has a set of options inside the osnoise directory, they are:
  - tracing_threshold: the minimum delta between two time() reads to be
    considered as noise, in us. When set to 0, the default value will
    be used, which is currently 5 us.
+ - osnoise/options: a set of on/off options that can be enabled by
+   writing the option name to the file or disabled by writing the option
+   name preceded with the 'NO_' prefix. For example, writing
+   NO_OSNOISE_WORKLOAD disables the OSNOISE_WORKLOAD option. The
+   special DEAFAULTS option resets all options to the default value.
 
 Additional Tracing
 ------------------
@@ -150,3 +155,10 @@ tracepoints is smaller than eight us reported in the sample_threshold.
 The reason roots in the overhead of the entry and exit code that happens
 before and after any interference execution. This justifies the dual
 approach: measuring thread and tracing.
+
+Running osnoise tracer without workload
+---------------------------------------
+
+By enabling the osnoise tracer with the NO_OSNOISE_WORKLOAD option set,
+the osnoise: tracepoints serve to measure the execution time of
+any type of Linux task, free from the interference of other tasks.
-- 
2.32.0