rtla: Add rtla timerlat documentation

Man page for rtla timerlat tool.

Link: https://lkml.kernel.org/r/78678b8d024bf5a3a79f831ac9441b96e8d2f56e.1639158831.git.bristot@kernel.org

Cc: Tao Zhou <tao.zhou@linux.dev>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Tom Zanussi <zanussi@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Daniel Bristot de Oliveira <bristot@kernel.org>
Cc: linux-rt-users@vger.kernel.org
Cc: linux-trace-devel@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Daniel Bristot de Oliveira 2021-12-10 19:11:31 +01:00 committed by Steven Rostedt
parent e7041c6b3c
commit 29380d4055
2 changed files with 67 additions and 0 deletions

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The **rtla timerlat** tool is an interface for the *timerlat* tracer. The
*timerlat* tracer dispatches a kernel thread per-cpu. These threads
set a periodic timer to wake themselves up and go back to sleep. After
the wakeup, they collect and generate useful information for the
debugging of operating system timer latency.
The *timerlat* tracer outputs information in two ways. It periodically
prints the timer latency at the timer *IRQ* handler and the *Thread*
handler. It also enable the trace of the most relevant information via
**osnoise:** tracepoints.

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================
rtla-timerlat
================
-------------------------------------------
Measures the operating system timer latency
-------------------------------------------
:Manual section: 1
SYNOPSIS
========
**rtla timerlat** [*MODE*] ...
DESCRIPTION
===========
.. include:: common_timerlat_description.rst
The *timerlat* tracer outputs information in two ways. It periodically
prints the timer latency at the timer *IRQ* handler and the *Thread* handler.
It also provides information for each noise via the **osnoise:** tracepoints.
The **rtla timerlat top** mode displays a summary of the periodic output
from the *timerlat* tracer. The **rtla hist hist** mode displays a histogram
of each tracer event occurrence. For further details, please refer to the
respective man page.
MODES
=====
**top**
Prints the summary from *timerlat* tracer.
**hist**
Prints a histogram of timerlat samples.
If no *MODE* is given, the top mode is called, passing the arguments.
OPTIONS
=======
**-h**, **--help**
Display the help text.
For other options, see the man page for the corresponding mode.
SEE ALSO
========
**rtla-timerlat-top**\(1), **rtla-timerlat-hist**\(1)
*timerlat* tracer documentation: <https://www.kernel.org/doc/html/latest/trace/timerlat-tracer.html>
AUTHOR
======
Written by Daniel Bristot de Oliveira <bristot@kernel.org>
.. include:: common_appendix.rst