From: Tomas Glozar Date: Fri, 10 Oct 2025 08:33:37 +0000 (+0200) Subject: Documentation/trace: Specify exact priority for timerlat X-Git-Tag: v6.19-rc1~184^2~33 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b9f6a40dc3f03f1d688faad7bf9b7f78c366d0dd;p=thirdparty%2Flinux.git 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 Acked-by: Steven Rostedt (Google) Signed-off-by: Jonathan Corbet Message-ID: <20251010083338.478961-9-tglozar@redhat.com> --- diff --git a/Documentation/trace/timerlat-tracer.rst b/Documentation/trace/timerlat-tracer.rst index 53a56823e903d..68d429d454a54 100644 --- a/Documentation/trace/timerlat-tracer.rst +++ b/Documentation/trace/timerlat-tracer.rst @@ -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