NAME
semmns — number of System V IPC system-wide semaphores
VALUES
Allowed values
Minimum: semmni
Maximum: 32767
DESCRIPTION
The
semmns
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
semmns
less than
semmni
(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
[ENOSPC]
error from
semget().
For more information about System V semaphores, refer to the
"Overview" 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.
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 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
tunables include
semaem,
semmap,
semmni,
semmns,
semmnu,
semmsl,
semume,
semvmx,
and
sysv_hash_locks.
Typically, a change in the
semmns
tunable does not require changes to other tunables.
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.
AUTHOR
semmns
was developed by AT&T.
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