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 ksi_alloc_max(5)                                           ksi_alloc_max(5)
                          Tunable Kernel Parameters



 NAME    [Toc]    [Back]
      ksi_alloc_max - system-wide limit of queued signals that can be
      allocated

 VALUES    [Toc]    [Back]
    Default
      NPROC * 8

    Allowed Values    [Toc]    [Back]
      32 through maxint (0x7fffffff)

    Recommended    [Toc]    [Back]
      NPROC * 8

 DESCRIPTION    [Toc]    [Back]
      ksi_alloc_max is the system-wide limit on the number of queued signals
      that can be allocated and in use.  ksi stands for "kernel signal
      information" and identifies entries with information about queued
      signals.  There is one per queued signal.  Queued signals are used by
      the sigqueue system call, timer expiration, POSIX real time message
      queues, and asynchronous I/O.  User generated signals (via kill and
      raise) are not queued.

    Who Is Expected to Change This Tunable?
      Anyone.

    Restrictions on Changing    [Toc]    [Back]
      None.  This tunable is dynamic.

    When Should the Value of This Tunable Be Raised?
      Frequent or heavy use of facilities which use queued signals, may
      require raising this value.  Since the default value is based on the
      number of processes but the usage is thread based, a large number of
      threads per process which use queued signals would require a raising
      the tunable value.  When [EAGAIN] is returned by applications using
      queued signals, this tunable should be raised.

    What Are the Side Effects of Raising the Value?
      Increased memory usage, but only if used.  Every allocated entry is 96
      bytes.

    When Should the Value of This Tunable Be Lowered?
      Only to control the applications' usage of queued signals.

    What Are the Side Effects of Lowering the Value?
      If too low, applications using queued signals may fail.

    What Other Tunable Values Should Be Changed at the Same Time?
      ksi_send_max to limit the number of queued signals per process.  Since
      ksi_alloc_max is per system based and ksi_send_max is per process
      based, the ksi_alloc_max tunable should always be greater.



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






 ksi_alloc_max(5)                                           ksi_alloc_max(5)
                          Tunable Kernel Parameters



      Note that the default value for ksi_send_max is 32, and for
      ksi_alloc_max is 'nproc * 8'.

 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]
      ksi_alloc_max was developed by HP.

 SEE ALSO    [Toc]    [Back]
      kill(2), sigqueue(2), ksi_send_max(5).


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