Documentation/tools/rtla/rtla-hwnoise.rst

Source file repositories/reference/linux-study-clean/Documentation/tools/rtla/rtla-hwnoise.rst

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Documentation/tools/rtla/rtla-hwnoise.rst
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Support Tooling And Documentation
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Support Tooling And Documentation: documentation
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Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

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.. SPDX-License-Identifier: GPL-2.0

.. |tool| replace:: hwnoise

============
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.txt

.. include:: common_top_options.txt

.. include:: common_options.txt

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.

Annotation

Implementation Notes