NAME
semmsl — maximum number of System V IPC semaphores per identifier
VALUES
Allowed values
Minimum: 1
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.
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 semaphore tunables include
semaem,
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 11i Version 1 the maximum number of semaphores per ID
was an undocumented constant 2048 in the header file
sys/sem.h.
Typically applications do not depend upon this limitation.
For those that were compiled with the old constant,
semmsl
tunable values higher than 2048 will generally not be a problem. However,
semmsl
tunable values lower than 2048 may cause other such applications
to fail. These should be recoded to obtain the current
semmsl
value from
pstat_getipc(2).
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 tunable values, consult the documentation
for the kernel software being installed.
For information about optional kernel software that was
factory installed on your system, see
HP-UX Release Notes
at
http://docs.hp.com.
AUTHOR
semmsl
was developed by AT&T.
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