msgmni(5)                                                         msgmni(5)
                          Tunable Kernel Parameters



 NAME    [Toc]    [Back]
      msgmni - maximum number of system-wide System V IPC message queues
      (IDs) allowed

 VALUES    [Toc]    [Back]
    Default
      512

    Failsafe    [Toc]    [Back]
      512

    Allowed Values    [Toc]    [Back]
      Minimum: 1

      Maximum: 32767

 DESCRIPTION    [Toc]    [Back]
      The msgmni tunable specifies the maximum number of system-wide System
      V IPC message queue identifiers (one per queue).  Each message queue
      created has an identifier (ID) and there is an upper limit of msgmni
      identifiers.

      Applications use the msgget() system call to create new queues.  If
      all IDs have been used, msgget() will return [ENOSPC].

      If a process acquires a message queue, but the process terminates
      without removing it, the queue and all its messages remain.  Abandoned
      message queues can be removed with the ipcrm command.  Message queue
      status can be monitored using the ipcs command.

      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 when applications require more queues.

    When Should the Value of This Tunable Be Lowered?
      Lower this tunable when the requirement for queues has diminished.

    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 and msgtql tunables, may



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






 msgmni(5)                                                         msgmni(5)
                          Tunable Kernel Parameters



      need adjustment along with changes to the msgmni 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]
      msgmni was developed by AT&T.

 SEE ALSO    [Toc]    [Back]
      ipcrm(1), ipcs(1), msgget(2), mesg(5), msgmap(5), msgmax(5),
      msgmnb(5), msgseg(5), msgssz(5), msgtql(5).


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