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Documentation/trace: Specify exact priority for timerlat 

The timerlat tracer documentation mentions that threads are created with
real-time priority, but does not mention which priority and scheduling
class is used.

Add the information so that users do not have to look it up in
trace_osnoise.c.

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: <20251010083338.478961-9-tglozar@redhat.com>
This commit is contained in:
Tomas Glozar 2025-10-10 10:33:37 +02:00 committed by Jonathan Corbet
parent 122a552b5b
commit b9f6a40dc3
1 changed files with 6 additions and 6 deletions
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12
Documentation/trace/timerlat-tracer.rst
View File

@ -43,12 +43,12 @@ It is possible to follow the trace by reading the trace file::
<...>-868 [001] .... 54.030347: #2 context thread timer_latency 4351 ns
The tracer creates a per-cpu kernel thread with real-time priority that
prints two lines at every activation. The first is the *timer latency*
observed at the *hardirq* context before the activation of the thread.
The second is the *timer latency* observed by the thread. The ACTIVATION
ID field serves to relate the *irq* execution to its respective *thread*
execution.
The tracer creates a per-cpu kernel thread with real-time priority
SCHED_FIFO:95 that prints two lines at every activation. The first is
the *timer latency* observed at the *hardirq* context before the activation
of the thread. The second is the *timer latency* observed by the thread.
The ACTIVATION ID field serves to relate the *irq* execution to its
respective *thread* execution.
The *irq*/*thread* splitting is important to clarify in which context
the unexpected high value is coming from. The *irq* context can be