semmns(5) [hpux man page]

semmns(5)							File Formats Manual							 semmns(5)

NAME

       semmns - number of System V IPC system-wide semaphores

VALUES

   Failsafe
   Default
   Allowed values
DESCRIPTION

       The  tunable  specifies the maximum total individual System V IPC system-wide semaphores which can be assigned by applications.	Semaphores
       are assigned in "sets" associated with an ID.  Thus semaphores can be distributed in any manner across the range of IDs with  one  or  more
       per ID.

       There is no reason to specify less than (the maximum number of identifiers) as each ID requires at least one semaphore.

       If an application attempts to create a semaphore set with more semaphores than are remaining, 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 applications require more total semaphores in the system.

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

   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 sets.  Lowering the tunable has no effect on any active semaphores in their respective sets, even if the new  tunable  value
       is  less  than  the  number of semaphores already created on the system.  However, no new semaphore sets may be created until the number of
       active semaphores on the system 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 Typically, a change in the tunable does
       not require changes 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.

       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), semmni(5), semmnu(5), semmsl(5), semume(5), semvmx(5), sysv_hash_locks(5).

							     Tunable Kernel Parameters							 semmns(5)

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)