mirror of
https://github.com/torvalds/linux
synced 2024-09-06 18:01:05 +00:00
Documentation/rtla: Add hwnoise man page
Add a man page for the new rtla hwnoise tool, mostly based in the rtla osnoise top. Link: https://lkml.kernel.org/r/27088e0f42a6129e9b75f789d78adff4171f2e79.1675805361.git.bristot@kernel.org Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org> Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com> Cc: Daniel Bristot de Oliveira <bristot@kernel.org> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Clark Williams <williams@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
parent
1f428356c3
commit
5dc3750e74
|
@ -17,6 +17,7 @@ behavior on specific hardware.
|
||||||
rtla-timerlat
|
rtla-timerlat
|
||||||
rtla-timerlat-hist
|
rtla-timerlat-hist
|
||||||
rtla-timerlat-top
|
rtla-timerlat-top
|
||||||
|
rtla-hwnoise
|
||||||
|
|
||||||
.. only:: subproject and html
|
.. only:: subproject and html
|
||||||
|
|
||||||
|
|
107
Documentation/tools/rtla/rtla-hwnoise.rst
Normal file
107
Documentation/tools/rtla/rtla-hwnoise.rst
Normal file
|
@ -0,0 +1,107 @@
|
||||||
|
.. SPDX-License-Identifier: GPL-2.0
|
||||||
|
|
||||||
|
============
|
||||||
|
rtla-hwnoise
|
||||||
|
============
|
||||||
|
------------------------------------------
|
||||||
|
Detect and quantify hardware-related noise
|
||||||
|
------------------------------------------
|
||||||
|
|
||||||
|
:Manual section: 1
|
||||||
|
|
||||||
|
SYNOPSIS
|
||||||
|
========
|
||||||
|
|
||||||
|
**rtla hwnoise** [*OPTIONS*]
|
||||||
|
|
||||||
|
DESCRIPTION
|
||||||
|
===========
|
||||||
|
|
||||||
|
**rtla hwnoise** collects the periodic summary from the *osnoise* tracer
|
||||||
|
running with *interrupts disabled*. By disabling interrupts, and the scheduling
|
||||||
|
of threads as a consequence, only non-maskable interrupts and hardware-related
|
||||||
|
noise is allowed.
|
||||||
|
|
||||||
|
The tool also allows the configurations of the *osnoise* tracer and the
|
||||||
|
collection of the tracer output.
|
||||||
|
|
||||||
|
OPTIONS
|
||||||
|
=======
|
||||||
|
.. include:: common_osnoise_options.rst
|
||||||
|
|
||||||
|
.. include:: common_top_options.rst
|
||||||
|
|
||||||
|
.. include:: common_options.rst
|
||||||
|
|
||||||
|
EXAMPLE
|
||||||
|
=======
|
||||||
|
In the example below, the **rtla hwnoise** tool is set to run on CPUs *1-7*
|
||||||
|
on a system with 8 cores/16 threads with hyper-threading enabled.
|
||||||
|
|
||||||
|
The tool is set to detect any noise higher than *one microsecond*,
|
||||||
|
to run for *ten minutes*, displaying a summary of the report at the
|
||||||
|
end of the session::
|
||||||
|
|
||||||
|
# rtla hwnoise -c 1-7 -T 1 -d 10m -q
|
||||||
|
Hardware-related Noise
|
||||||
|
duration: 0 00:10:00 | time is in us
|
||||||
|
CPU Period Runtime Noise % CPU Aval Max Noise Max Single HW NMI
|
||||||
|
1 #599 599000000 138 99.99997 3 3 4 74
|
||||||
|
2 #599 599000000 85 99.99998 3 3 4 75
|
||||||
|
3 #599 599000000 86 99.99998 4 3 6 75
|
||||||
|
4 #599 599000000 81 99.99998 4 4 2 75
|
||||||
|
5 #599 599000000 85 99.99998 2 2 2 75
|
||||||
|
6 #599 599000000 76 99.99998 2 2 0 75
|
||||||
|
7 #599 599000000 77 99.99998 3 3 0 75
|
||||||
|
|
||||||
|
|
||||||
|
The first column shows the *CPU*, and the second column shows how many
|
||||||
|
*Periods* the tool ran during the session. The *Runtime* is the time
|
||||||
|
the tool effectively runs on the CPU. The *Noise* column is the sum of
|
||||||
|
all noise that the tool observed, and the *% CPU Aval* is the relation
|
||||||
|
between the *Runtime* and *Noise*.
|
||||||
|
|
||||||
|
The *Max Noise* column is the maximum hardware noise the tool detected in a
|
||||||
|
single period, and the *Max Single* is the maximum single noise seen.
|
||||||
|
|
||||||
|
The *HW* and *NMI* columns show the total number of *hardware* and *NMI* noise
|
||||||
|
occurrence observed by the tool.
|
||||||
|
|
||||||
|
For example, *CPU 3* ran *599* periods of *1 second Runtime*. The CPU received
|
||||||
|
*86 us* of noise during the entire execution, leaving *99.99997 %* of CPU time
|
||||||
|
for the application. In the worst single period, the CPU caused *4 us* of
|
||||||
|
noise to the application, but it was certainly caused by more than one single
|
||||||
|
noise, as the *Max Single* noise was of *3 us*. The CPU has *HW noise,* at a
|
||||||
|
rate of *six occurrences*/*ten minutes*. The CPU also has *NMIs*, at a higher
|
||||||
|
frequency: around *seven per second*.
|
||||||
|
|
||||||
|
The tool should report *0* hardware-related noise in the ideal situation.
|
||||||
|
For example, by disabling hyper-threading to remove the hardware noise,
|
||||||
|
and disabling the TSC watchdog to remove the NMI (it is possible to identify
|
||||||
|
this using tracing options of **rtla hwnoise**), it was possible to reach
|
||||||
|
the ideal situation in the same hardware::
|
||||||
|
|
||||||
|
# rtla hwnoise -c 1-7 -T 1 -d 10m -q
|
||||||
|
Hardware-related Noise
|
||||||
|
duration: 0 00:10:00 | time is in us
|
||||||
|
CPU Period Runtime Noise % CPU Aval Max Noise Max Single HW NMI
|
||||||
|
1 #599 599000000 0 100.00000 0 0 0 0
|
||||||
|
2 #599 599000000 0 100.00000 0 0 0 0
|
||||||
|
3 #599 599000000 0 100.00000 0 0 0 0
|
||||||
|
4 #599 599000000 0 100.00000 0 0 0 0
|
||||||
|
5 #599 599000000 0 100.00000 0 0 0 0
|
||||||
|
6 #599 599000000 0 100.00000 0 0 0 0
|
||||||
|
7 #599 599000000 0 100.00000 0 0 0 0
|
||||||
|
|
||||||
|
SEE ALSO
|
||||||
|
========
|
||||||
|
|
||||||
|
**rtla-osnoise**\(1)
|
||||||
|
|
||||||
|
Osnoise tracer documentation: <https://www.kernel.org/doc/html/latest/trace/osnoise-tracer.html>
|
||||||
|
|
||||||
|
AUTHOR
|
||||||
|
======
|
||||||
|
Written by Daniel Bristot de Oliveira <bristot@kernel.org>
|
||||||
|
|
||||||
|
.. include:: common_appendix.rst
|
Loading…
Reference in a new issue