LATENCY
Section: User Commands (1)
Index
Return to Main Contents
BSD mandoc
Mac OS X
NAME
latency
- monitors scheduling and interrupt latency
SYNOPSIS
latency
[-rt
]
[-c codefile
]
[-l logfile
]
[-st threshold
]
[-it threshold
]
[-s sleep_in_usecs
]
[-d decrementer_in_usecs
]
[-n kernel
]
DESCRIPTION
latency
provides scheduling and interrupt latency statistics.
The arguments are as follows:
- -rt
-
Set real time scheduling policy. Default policy is timeshare.
- -c
-
When the
-c
option is specified, it takes a path to a
codefile
that
contains the mappings for the system calls. This option
overrides the default location of the system call codefile
which is found in /usr/share/misc/trace.codes.
- -l
-
Specifies a
logfile
that is written to when either the interrupt or scheduling
latency is exceeded.
- -st
-
Set the scheduler latency threshold in microseconds. If latency
exceeds this, and a logfile has been specified, a record
of what occurred during this time is recorded.
- -it
-
Set the interrupt latency threshold in microseconds. If latency
exceeds this, and a logfile has been specified, a record
of what occurred during this time is recorded.
- -s
-
The
-s
option sets the timer. It takes microseconds as an argument,
the default timer is set to 1000 microseconds.
- -d
-
The
-d
option sets the decrementer. It takes microseconds as an argument.
The decrementer is set back to the system default on exit.
- -n
-
By default,
latency
acts on the default /mach_kernel. This option
allows you to specify an alternate booted kernel.
The data columns displayed are as follows:
- SCHEDULER
-
The number of context switches that fall
within the described delay.
- INTERRUPTS
-
The number of interrupts that fall
within the described delay.
The
latency
command is also SIGWINCH savvy, so adjusting your window geometry will change
the list of delay values displayed.
SAMPLE USAGE
latency -rt -st 20000 -it 1000 -l /var/tmp/latency.log
latency
will set the realtime scheduling policy. The threshold for the scheduler is set to
20000 microseconds. The threshold for interrupts is set to 1000
microseconds. Latencies that exceed these thresholds will be logged
in /var/tmp/latency.log.
SEE ALSO
top(1)
fs_usage1
sc_usage1
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- SAMPLE USAGE
-
- SEE ALSO
-
This document was created by
man2html,
using the manual pages.
Time: 04:29:23 GMT, April 24, 2025