LATENCYTOP(8) System Manager's Manual LATENCYTOP(8)NAME
latencytop - a tool for developers to visualize system latencies
SYNOPSIS
latencytop [--unknown] [processes...]
DESCRIPTION
This manual page documents briefly the latencytop command.
latencytop is a Linux* tool for software developers (both kernel and userspace), aimed at identifying where in the system latency is hap-
pening, and what kind of operation/action is causing the latency to happen so that the code can be changed to avoid the worst latency hic-
cups.
LatencyTOP focuses on the cases where the applications want to run and execute useful code, but there's some resource that's not currently
available (and the kernel then blocks the process). This is done both on a system level and on a per process level, so that you can see
what's happening to the system, and which process is suffering and/or causing the delays.
You can walk the processes by using the cursor keys. If you press s followed by a letter, then only active processes starting with that
lettter are displayed and walked. If you press s followed by 0 then that filter is reset.
If you press f then LatencyTop displays a list of all processes currently waiting for an fsync to finish. Pressing f again returns you to
the normal operating mode of LatencyTop.
SEE ALSO powertop(1)
The program is more fully described at http://www.latencytop.org
AUTHOR
latencytop was written by Arjan van de Ven <arjan@linux.intel.com>.
This manual page was written by Giacomo Catenazzi <cate@debian.org>, for the Debian project (but may be used by others).
November 9, 2008 LATENCYTOP(8)
Check Out this Related Man Page
LATENCY(1) Xenomai LATENCY(1)NAME
latency - Xenomai timer latency benchmark
SYNOPSIS
latency [options]
DESCRIPTION
latency is part of the Xenomai test suite. It is a timer latency benchmark program. The system must run a suitable Xenomai enabled kernel
with the respective module (xeno_timerbench).
OPTIONS
latency accepts the following options:
-h print histograms of min, avg, max latencies
-s print statistics of min, avg, max latencies
-H <histogram-size>
default = 200, increase if your last bucket is full
-B <bucket-size>
default = 1000ns, decrease for more resolution
-p <period_us>
sampling period
-l <data-lines per header>
default=21, 0 to supress headers
-T <test_duration_seconds>
default=0, so ^C to end
-q supresses RTD, RTH lines if -T is used
-D <testing_device_no>
number of testing device, default=0
-t <test_mode>
0=user task (default), 1=kernel task, 2=timer IRQ
-f freeze trace for each new max latency
-c <cpu>
pin measuring task down to given CPU
-P <priority>
task priority (test mode 0 and 1 only)
AUTHOR
latency was written by Philippe Gerum <rpm@xenomai.org>. This man page was written by Roland Stigge <stigge@antcom.de>.
2.6.0 2008-04-19 LATENCY(1)
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