latencytop(1M) System Administration Commands latencytop(1M)NAMElatencytop - report latency-related statistics in system and in appli‐
cations
SYNOPSISlatencytop [-t interval] [-o log_file] [-k log_level]
[-f [no]feature,...] [-l log_interval] [-h]
DESCRIPTION
LatencyTOP is an observability tool that reports statistics about
latencies in the system and in applications. The tool reports statis‐
tics about where and what kind of latencies are happening in the system
and in the applications that are running on the system. The statistics
then can be used to improve performance throughput of applications and
system, as you remove the identified latencies.
The tool analyzes system activity periodically and displays the data in
the output window. Two types of latencies are tracked: an LWP going in
and out of sleep and an LWP spinning order to acquire a synchronization
object. The tool uses the Solaris DTrace framework to collect the sta‐
tistics corresponding to these two scenarios of inactivity of the sys‐
tem and application LWPs.
The output window is divided into two sections. An upper part displays
the system-wide statistics, while the lower part displays statistics
about individual processes. The user can navigate the list of processes
(using the left- and right-arrow keys) and select the list they are
interested in. The tool will then display statistics about that
selected process in the lower part of the window. If the t or T key is
pressed, the tool displays the LWP-specific view of that selected
process. The t or T key can be used to toggle between the process-view
and the thread-view.
During execution, a user can force a refresh of the analysis by press‐
ing the r or R key. The interval time is restored to the default or to
a specified value (if -t was used). To quit the application, the user
must press the q or Q key.
OPTIONS
The following options are supported:
-f, --feature [no]feature1,[no]feature2,...
Enables/disables features in LatencyTOP. Features can be only one
of the following:
[no]filter
Filter large interruptible latencies, for example, sleep. The
default is off.
[no]sched
Monitors sched (PID=0). The default is off.
[no]sobj
Monitors synchronize objects. The default is on.
[no]low
Lower overhead by sampling small latencies. Enabling this fea‐
ture will lower CPU utilization by estimating small latencies
statistically. Use it for heavy workloads such as a very busy
web server. The default is off.
-h
Displays the command's usage.
-k log_level
Specifies the level of logging in the log file. Valid values are:
0 none (default)
1 unknown
2 all
-l [log_interval]
Writes data to the log file every log_interval seconds; log_inter‐
val must be greater than 60.
-o log_file
Specifies the log file where output will be written. The default
log file is /var/log/latencytop.log.
-t interval
Specifies the interval, in seconds, at which the tool collects sta‐
tistics from the system. The possible values are between 1 and 60;
the default is 5 seconds.
EXAMPLES
Example 1 Running the Tool
The following command launches the tool with default values for
options.
% latencytop
Example 2 Setting the Interval
The following command sets the sampling interval to two seconds.
% latencytop-t 2
Example 3 Specifying the Log File
The following command sets the log file to /tmp/latencytop.log.
% latencytop-o /tmp/latencytop.log
Example 4 Specifying the Log Level
The following command sets the log level to all.
% latencytop-l 2
Example 5 Enabling Tracing of Latencies
The following command enables the tracing of latencies caused by syn‐
chronization objects.
% latencytop-f sobj
EXIT STATUS
0
Successful operation.
1
An error occurred.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Architecture │x86, SPARC │
├─────────────────────────────┼─────────────────────────────┤
│Availability │diagnostic/latencytop │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Volatile │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOdtrace(1M), kstat(1M), attributes(5)USAGE
You must have DTrace privileges to run LatencyTOP.
SunOS 5.11 29 Sep 2009 latencytop(1M)
