HP-UX Reference (11i v2 03/08) - 5 Miscellaneous Topics, 7 Device (Special) Files, 9 General Information, Index (vol 9)
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semmsl(5) semmsl(5)
(Tunable Kernel Parameters)
NAME
semmsl - maximum number of System V IPC semaphores per identifier
VALUES
Failsafe
2048
Default
2048
Allowed values
Minimum: 1
Maximum: 10240
DESCRIPTION
The semmsl tunable specifies the maximum number of individual System V IPC semaphores per sema-
phore 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 vari-
ables. 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).
AUTHOR
semmsl was developed by AT&T.
SEE ALSO
semget(2), sema(5), semaem(5), semmns(5), semmni(5), semmnu(5), semume(5), semvmx(5),
sysv_hash_locks(5).
HP-UX 11i Version 2: August 2003 − 1 − Hewlett-Packard Company Section 5−−265