sema(5)                                                             sema(5)
                          Tunable Kernel Parameters



 NAME    [Toc]    [Back]
      sema - enable or disable System V IPC semaphores at boot time

 DESCRIPTION    [Toc]    [Back]
      The sema tunable is obsolete.  The System V IPC semaphore subsystem is
      always enabled.

    Overview    [Toc]    [Back]
      System V IPC is comprised of mechanisms for arbitrary processes to
      send and receive data messages, share virtual address space and use
      semaphores to synchronize execution.

      A System V semaphore is a synchronization method for user processes to
      synchronize or serialize access to common data and resources.  Each
      semaphore "set" has an ID, but each set can contain one or more
      independent semaphores.

      Semaphore sets are created or initially accessed through semget()
      using an application-specified "key", which can be generated by
      ftok().  Operations on the set are performed through semop() and
      semctl().  Semaphore sets are removed through semctl() or the ipcrm
      command.

 WARNINGS    [Toc]    [Back]
      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]
      sema was developed by AT&T.

 SEE ALSO    [Toc]    [Back]
      ipcs(1), ipcrm(1), semget(2), semop(2), semctl(2), semaem(5),
      semmni(5), semmns(5), semmnu(5), semmsl(5), semume(5), semvmx(5),
      sysv_hash_locks(5).


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