semmnu(5)							File Formats Manual							 semmnu(5)

NAME

       semmnu - maximum number of System V IPC undo structures for processes

VALUES

   Failsafe
   Default
   Allowed values
DESCRIPTION

       Note:   If  the	DynSysVSem  optional product bundle is installed then this tunable is ignored and has no effect.  Applications can perform
       "undo" operations without any system imposed limits.

       The tunable specifies the maximum number of System V IPC system-wide processes that can have "undo" operations pending at any given time.

       If an application exhausts this limit, 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 are ignored and have no effect.

   When Should the Value of This Tunable Be Raised?
       When the set of application processes which use semaphore "undo" semantics exceeds the limit.

   When Should the Value of This Tunable Be Lowered?
       If requirements for semaphore "undo" semantics has significantly decreased, or for  limiting  protection  on  run-away  applications  which
       change semaphores.

   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 Generally, a change in does  not  require
       attention to other tunables.

       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.

       A two-dimensional table of undo structures (~8 bytes each) is allocated in kernel memory at boot time.  This memory is reserved whether	or
       not it is used.

       The  table  dimensions  are and (maximum number of per-process undo structures).  So the memory requirement is approximately the product of
       those two tunables and the structure size.  Use care when setting these two tunables, as they can have a profound effect on memory utiliza-
       tion, due to the multiplicative effect.

       Note:   If  the	DynSysVSem  optional  product bundle is installed then and are ignored and have no effect.  No memory is allocated at boot
       time.  Instead "undo" structures are dynamically allocated when needed by the application and deallocated when no longer needed.

       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

       semop(2), sema(5), semaem(5), semmns(5), semmni(5), semmsl(5), semume(5), semvmx(5), sysv_hash_locks(5).

							     Tunable Kernel Parameters							 semmnu(5)