latencytop(1m)

1latencytop(1M)          System Administration Commands          latencytop(1M)
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NAME

6       latencytop  - report latency-related statistics in system and in appli‐
7       cations
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SYNOPSIS

10       latencytop [-t interval] [-o log_file] [-k log_level]
11            [-f [no]feature,...] [-l log_interval] [-h]
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DESCRIPTION

15       LatencyTOP is an  observability  tool  that  reports  statistics  about
16       latencies  in  the system and in applications. The tool reports statis‐
17       tics about where and what kind of latencies are happening in the system
18       and  in the applications that are running on the system. The statistics
19       then can be used to improve performance throughput of applications  and
20       system, as you remove the identified latencies.
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23       The tool analyzes system activity periodically and displays the data in
24       the output window. Two types of latencies are tracked: an LWP going  in
25       and out of sleep and an LWP spinning order to acquire a synchronization
26       object. The tool uses the Solaris DTrace framework to collect the  sta‐
27       tistics  corresponding to these two scenarios of inactivity of the sys‐
28       tem and application LWPs.
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31       The output window is divided into two sections. An upper part  displays
32       the  system-wide  statistics,  while the lower part displays statistics
33       about individual processes. The user can navigate the list of processes
34       (using  the  left-  and  right-arrow keys) and select the list they are
35       interested in.  The  tool  will  then  display  statistics  about  that
36       selected  process in the lower part of the window. If the t or T key is
37       pressed, the tool displays  the  LWP-specific  view  of  that  selected
38       process.  The t or T key can be used to toggle between the process-view
39       and the thread-view.
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42       During execution, a user can force a refresh of the analysis by  press‐
43       ing  the r or R key. The interval time is restored to the default or to
44       a specified value (if -t was used). To quit the application,  the  user
45       must press the q or Q key.
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OPTIONS

48       The following options are supported:
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50       -f, --feature [no]feature1,[no]feature2,...
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52           Enables/disables  features  in LatencyTOP. Features can be only one
53           of the following:
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55           [no]filter
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57               Filter large interruptible latencies, for example,  sleep.  The
58               default is off.
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61           [no]sched
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63               Monitors sched (PID=0). The default is off.
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66           [no]sobj
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68               Monitors synchronize objects. The default is on.
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71           [no]low
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73               Lower  overhead by sampling small latencies. Enabling this fea‐
74               ture will lower CPU utilization by estimating  small  latencies
75               statistically.  Use  it for heavy workloads such as a very busy
76               web server. The default is off.
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80       -h
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82           Displays the command's usage.
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85       -k log_level
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87           Specifies the level of logging in the log file. Valid values are:
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89           0    none (default)
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92           1    unknown
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95           2    all
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99       -l [log_interval]
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101           Writes data to the log file every log_interval seconds;  log_inter‐
102           val must be greater than 60.
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105       -o log_file
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107           Specifies  the  log  file where output will be written. The default
108           log file is /var/log/latencytop.log.
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111       -t interval
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113           Specifies the interval, in seconds, at which the tool collects sta‐
114           tistics  from the system. The possible values are between 1 and 60;
115           the default is 5 seconds.
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EXAMPLES

119       Example 1 Running the Tool
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122       The following  command  launches  the  tool  with  default  values  for
123       options.
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126         % latencytop
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130       Example 2 Setting the Interval
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133       The following command sets the sampling interval to two seconds.
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136         % latencytop -t 2
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140       Example 3 Specifying the Log File
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143       The following command sets the log file to /tmp/latencytop.log.
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146         % latencytop -o /tmp/latencytop.log
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150       Example 4 Specifying the Log Level
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153       The following command sets the log level to all.
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156         % latencytop -l 2
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160       Example 5 Enabling Tracing of Latencies
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163       The  following  command enables the tracing of latencies caused by syn‐
164       chronization objects.
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167         % latencytop -f sobj
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EXIT STATUS

172       0
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174           Successful operation.
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177       1
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179           An error occurred.
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ATTRIBUTES

183       See attributes(5) for descriptions of the following attributes:
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188       ┌─────────────────────────────┬─────────────────────────────┐
189       │      ATTRIBUTE TYPE         │      ATTRIBUTE VALUE        │
190       ├─────────────────────────────┼─────────────────────────────┤
191       │Architecture                 │x86, SPARC                   │
192       ├─────────────────────────────┼─────────────────────────────┤
193       │Availability                 │SUNWlatencytop               │
194       ├─────────────────────────────┼─────────────────────────────┤
195       │Interface Stability          │Volatile                     │
196       └─────────────────────────────┴─────────────────────────────┘
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USAGE

202       You must have DTrace privileges to run LatencyTOP.
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206SunOS 5.11                        29 Sep 2009                   latencytop(1M)