NAME
semmsl — maximum number of System V IPC semaphores per identifier
VALUES
Allowed values
Minimum: 2048
Maximum: 10240
DESCRIPTION
The
semmsl
tunable specifies the maximum number of individual System V IPC semaphores
per semaphore identifier (ID).
If an application attempts to exceed this limit, it will receive an
[EINVAL]
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
This tunable, although dynamic, can only be increased.
When Should the Value of This Tunable Be Raised?
If applications require a larger number of semaphores per ID.
When Should the Value of This Tunable Be Lowered?
If application requirements for semaphores per ID has decreased
or there is a need to protect against ill-behaved applications.
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.
Specifically, a change in the
semmsl
tunable may require a change in the
semmns
tunable.
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.
Prior to HP-UX release 11.11 the maximum number of semaphores per ID
was an undocumented constant 2048 in the header file
sys/sem.h.
Typically applications don't depend upon this limitation (higher
limits do not matter to them).
However, if you have such an application, you may want to keep
the default of 2048 for this tunable.
AUTHOR
semmsl
was developed by AT&T.
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