Manual Pages for UNIX Operating System command usage for man latencytop

System Administration Commands                     latencytop(1M)



NAME
     latencytop - report latency-related statistics in system and
     in applications

SYNOPSIS
     latencytop [-t interval] [-o log_file] [-k log_level]
          [-f [no]feature,...] [-l log_interval] [-h]
          [ -s pid=PID | pgid=PGID ]


DESCRIPTION
     LatencyTOP is an observability tool that reports  statistics
     about  latencies in the system and in applications. The tool
     reports statistics 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  spin-
     ning  order  to  acquire  a synchronization object. The tool
     uses the Solaris DTrace framework to collect the  statistics
     corresponding  to  these  two scenarios of inactivity of the
     system 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 tog-
     gle between the process-view and the thread-view.


     During execution, a user can force a refresh of the analysis
     by pressing 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



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System Administration Commands                     latencytop(1M)



         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  feature will lower CPU utilization by estimat-
             ing 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_interval must be greater than 60.



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System Administration Commands                     latencytop(1M)



     -o log_file

         Specifies the log file where output will be written. The
         default log file is /var/log/latencytop.log.


     -s pid=PID | pgid=PGID

         Tracks only the specified process or the specified  pro-
         cess  group  and displays data related only to that pro-
         cess or the process group.


     -t interval

         Specifies the interval, in seconds, at  which  the  tool
         collects statistics 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




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System Administration Commands                     latencytop(1M)



     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 synchronization objects.


       % latencytop -f sobj



     Example 6 Displaying Data for a Process Group


     The following command  displays  trace  date  for  processes
     belonging to Process Group 630.


       % latencytop -s pgid=630



EXIT STATUS
     0

         Successful operation.


     1

         An error occurred.


ATTRIBUTES
     See attributes(5) for descriptions of the  following  attri-
     butes:









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System Administration Commands                     latencytop(1M)



     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | Architecture                | x86, SPARC                  |
    |_____________________________|_____________________________|
    | Availability                | diagnostic/latencytop       |
    |_____________________________|_____________________________|
    | Interface Stability         | Volatile                    |
    |_____________________________|_____________________________|


SEE ALSO
     dtrace(1M), kstat(1M), attributes(5)

USAGE
     You must have DTrace privileges to run LatencyTOP.







































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