msgtql(5)                                                         msgtql(5)
                          Tunable Kernel Parameters



 NAME    [Toc]    [Back]
      msgtql - maximum number of System V IPC messages in the system at any
      time

 VALUES    [Toc]    [Back]
    Default
      1024

    Failsafe    [Toc]    [Back]
      1024

    Allowed values    [Toc]    [Back]
      Minimum: 1

      Maximum: msgseg

    Recommended values    [Toc]    [Back]
      The largest number of messages expected.

 DESCRIPTION    [Toc]    [Back]
      The msgtql tunable specifies the maximum total system-wide individual
      messages across all message queues.  Every message has a header to
      specify message type and location and the total number of headers is
      limited by msgtql.

      Note that if a msgsnd() system call attempts to exceed the limit
      imposed by msgtql, it will block until message space becomes available
      or return [EAGAIN] if IPC_NOWAIT is set.

      Other kernel tunables may limit the maximum number of messages
      supported.  Limiting factors can be msgmnb, the maximum number of
      bytes in a queue, or msgseg, the maximum number of message segments.

      For more information about System V message queues, refer to the
      Overview section of the mesg(5) manpage.

    Who Is Expected to Change This Tunable?
      Anyone.

    Restrictions on Changing    [Toc]    [Back]
      Changes to this tunable take effect at the next reboot.

    When Should the Value of This Tunable Be Raised?
      Raise this tunable if applications block too frequently in msgsnd(),
      requiring more total messages be held in the kernel message queues.

    When Should the Value of This Tunable Be Lowered?
      Lower this tunable when applications no longer require as many total
      messages.





 Hewlett-Packard Company            - 1 -      HP-UX 11i Version 2: Sep 2004






 msgtql(5)                                                         msgtql(5)
                          Tunable Kernel Parameters



    What Other Tunable Values Should Be Changed at the Same Time?
      All the System V message queue tunables are interrelated and should
      not be treated as independent variables.  The set must be evaluated as
      a system to ensure the tunables reflect the application requirements.
      The message tunables include msgmap, msgmax, msgmnb, msgmni, msgseg,
      msgssz, and msgtql.  Specifically, the msgseg or msgssz tunables may
      need to be adjusted along with the msgtql tunable.

 WARNINGS    [Toc]    [Back]
      All HP-UX kernel tunable parameters are release specific.  This
      parameter may be removed or have its meaning changed in future
      releases of HP-UX.

      Installation of optional kernel software, from HP or other vendors,
      may cause changes to tunable parameter values.  After installation,
      some tunable parameters may no longer be at the default or recommended
      values.  For information about the effects of installation on tunable
      values, consult the documentation for the kernel software being
      installed. For information about optional kernel software that was
      factory installed on your system, see HP-UX Release Notes at
      http://docs.hp.com.

 AUTHOR    [Toc]    [Back]
      msgtql was developed by AT&T.

 SEE ALSO    [Toc]    [Back]
      msgsnd(2), mesg(5), msgmap(5), msgmax(5), msgmnb(5), msgmni(5),
      msgseg(5), msgssz(5).


 Hewlett-Packard Company            - 2 -      HP-UX 11i Version 2: Sep 2004