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semmni(5)							     semmni(5)

NAME
       semmni - number of System V IPC system-wide semaphore identifiers

VALUES
   Failsafe
   Default
   Allowed values
DESCRIPTION
       The  tunable  specifies	the maximum number of System V IPC system-wide
       semaphore sets (and identifiers) which can exist at any given time.   A
       single identifier (ID) is returned for each system call to create a new
       set of one or more (up to semaphores.

       If an application attempts to create a semaphore set when all IDs  have
       previously been allocated, it will receive an error from

       For more information about System V semaphores, refer to the section of
       the sema(5) manpage.

   Who Is Expected to Change This Tunable?
       Anyone.

   Restrictions on Changing
       Changes to this tunable take effect at the next reboot.

       Note:  If the DynSysVSem optional  product  bundle  is  installed  then
       changes to this tunable take effect immediately.

   When Should the Value of This Tunable Be Raised?
       If  there  is  a	 requirement of more total unique semaphore IDs in the
       system, or one or more applications require more semaphore IDs.	 There
       is  no reason to specify more system-wide identifiers than the total of
       the semaphores.

   When Should the Value of This Tunable Be Lowered?
       If requirements for semaphore sets (IDs) has  significantly  decreased,
       or  there  is  a	 need to hard-limit applications from acquiring larger
       numbers of semaphore IDs.

   What Are the Side Effects of Lowering the Value?
       The following side effect applies only if the DynSysVSem optional prod‐
       uct bundle is installed.

       If  DynSysVSem  is  installed,  lowering	 the  value  of	 this  tunable
       increases the risk of application failure due to the inability to  cre‐
       ate  more semaphore identifiers.	 Lowering the tunable has no effect on
       any active semaphore identifiers, even if the new tunable value is less
       than the number of semaphore identifiers already created on the system.
       However, no new semaphore identifiers may be created until  the	number
       of active semaphore identifiers falls below the setting of

   What Other Tunable Values Should Be Changed at the Same Time?
       All  the System V semaphore tunables are interrelated and should not be
       treated as independent variables.  The tunables must be evaluated as  a
       system  to ensure they reflect the application requirements.  The sema‐
       phore tunables include and Specifically, changes	 in  the  tunable  may
       also  require  changes in the tunable.  Very significant changes in may
       also require changes in the tunable.

       Note:  If the DynSysVSem optional product bundle is installed then  the
       and tunables are ignored and have no effect.

WARNINGS
       All HP-UX kernel tunable parameters are release specific.  This parame‐
       ter 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 val‐
       ues.  For information about the effects of installation on tunable val‐
       ues, consult the documentation for the kernel software being installed.
       For  information	 about	optional  kernel  software  that  was  factory
       installed on your system, see at

AUTHOR
       was developed by AT&T.

SEE ALSO
       semget(2),   sema(5),   semaem(5),   semmns(5),	semmnu(5),  semmsl(5),
       semume(5), semvmx(5), sysv_hash_locks(5).

			   Tunable Kernel Parameters		     semmni(5)

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