nproc(5)                                                           nproc(5)
                          Tunable Kernel Parameters



 NAME    [Toc]    [Back]
      nproc - limits the number of processes allowed to exist simultaneously

 VALUES    [Toc]    [Back]
    Failsafe
      4200

    Default    [Toc]    [Back]
      4200

    Allowed values    [Toc]    [Back]
      100 - 30000

      This may be set higher, but more will not be used.  Setting nproc
      below 110 will interfere with the systems ability to execute in
      multi-user mode.  Some configurations may have a higher minimum.

      nproc must be greater than nkthread + 100.

      nproc must be greater than maxuprc + 5.

    Recommended values    [Toc]    [Back]
      1000 processes per processor.

 DESCRIPTION    [Toc]    [Back]
      The nproc tunable controls the absolute number of processes allowed on
      a system at any given time.  Increasing it will allow more processes,
      and lowering it will restrict the number of processes.

      It can be determined that nproc is too low when the proc: table is
      full message is seen in the message buffer.  The message buffer can be
      read via dmesg or syslog.  This message indicates that an application
      was unable to create a new process.  Setting nproc too low can cause
      application failures due to an inability to fork new processes.

      It can be determined how many processes have been used simultaneously
      by calling pstat_dynamic and examining the psd_numprocsallocd.  This
      field indicates the "high water" mark of the number of processes that
      have been simultaneously used.

    Who Is Expected to Change This Tunable?
      Anyone expecting to run large numbers of processes.

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

    When Should the Value of This Tunable Be Raised?
      The tunable should be increased when running large numbers of
      processes simultaneously.





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






 nproc(5)                                                           nproc(5)
                          Tunable Kernel Parameters



    What are the Side Effects of Raising the Value?
      None.

    When Should the Value of This Tunable Be Lowered?
      The value should be lowered only to limit the number of processes on
      the system, or when there is memory pressure and the value of nproc is
      far above the expected usage.

    What are the Side Effects of Lowering the Value?
      Increased risk of application failure due to the inability to fork new
      processes.

    What Other Tunable Values Should Be Changed at the Same Time?
      nkthread must be strictly greater than nproc.  Default equations
      ensure this, as well as runtime kernel checks.

      nfile and ninode should be increased (and are not by default) to allow
      applications to manipulate files.

      ksi_alloc_max should be increased, as the default formula is multiple
      of nproc.

      maxuprc must be less than nproc.

      Some of these other tunables used to adjust automatically with changes
      in nproc.  These adjustments must now be made explicitly.

      Other tunables may require a reboot to take effect.  So, dramatic
      increases in nproc without reboot should be made with caution.

 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]
      nproc was developed by HP.

 SEE ALSO    [Toc]    [Back]
      ksi_alloc_max(5), maxuprc(5), nfile(5), ninode(5), nkthread(5).


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