semmni(5)							File Formats Manual							 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 product bundle is installed.

       If DynSysVSem is installed, lowering the value of this tunable increases the risk of application failure due to	the  inability	to  create
       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 semaphore 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 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 tun-
       able values, 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)