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)
