rtla-osnoise

Measure the operating system noise

Manual section:

1

SYNOPSIS

rtla osnoise [MODE] ...

DESCRIPTION

The rtla osnoise tool is an interface for the osnoise tracer. The osnoise tracer dispatches a kernel thread per-cpu. These threads read the time in a loop while with preemption, softirq and IRQs enabled, thus allowing all the sources of operating system noise during its execution. The osnoise’s tracer threads take note of the delta between each time read, along with an interference counter of all sources of interference. At the end of each period, the osnoise tracer displays a summary of the results.

The osnoise tracer outputs information in two ways. It periodically prints a summary of the noise of the operating system, including the counters of the occurrence of the source of interference. It also provides information for each noise via the osnoise: tracepoints. The rtla osnoise top mode displays information about the periodic summary from the osnoise tracer. The rtla osnoise hist mode displays information about the noise using the osnoise: tracepoints. For further details, please refer to the respective man page.

MODES

top

Prints the summary from osnoise tracer.

hist

Prints a histogram of osnoise 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-osnoise-top(1), rtla-osnoise-hist(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>

SIGINT BEHAVIOR

On the first SIGINT, RTLA exits after collecting all outstanding samples up to the point of receiving the signal.

When receiving more than one SIGINT, RTLA discards any outstanding samples, and exits while displaying only samples that have already been processed.

If SIGINT is received during RTLA cleanup, RTLA exits immediately via the default signal handler.

Note: For the purpose of SIGINT behavior, the expiry of duration specified via the -d/--duration option is treated as equivalent to receiving a SIGINT. For example, a SIGINT received after duration expired but samples have not been processed yet will drop any outstanding samples.

Also note that when using the timerlat tool in BPF mode, samples are processed in-kernel; RTLA only copies them out to display them to the user. A second SIGINT does not affect in-kernel sample aggregation.

EXIT STATUS

0  Passed: the test did not hit the stop tracing condition
1  Error: invalid argument
2  Failed: the test hit the stop tracing condition

REPORTING BUGS

Report bugs to <linux-kernel@vger.kernel.org> and <linux-trace-devel@vger.kernel.org>

LICENSE

rtla is Free Software licensed under the GNU GPLv2

COPYING

Copyright (C) 2021 Red Hat, Inc. Free use of this software is granted under the terms of the GNU Public License (GPL).