NAME
semaem — maximum cumulative value changes per System V IPC semop() call
VALUES
Allowed values
Minimum: 0
Maximum: semvmx
or less than or equal to
32767.
DESCRIPTION
The
semaem
tunable specifies the maximum cumulative value change for all System V IPC
semaphores changed by each undo within any one single
semop()
operation.
This refers to the cumulative sum of the undo value changes for each individual
semaphore.
Any
semop()
call which attempts to exceed this limit will return
ERANGE.
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 an application is expected to hold and change large numbers of semaphores
and large semaphore value changes as compared with the default value.
When Should the Value of This Tunable Be Lowered?
If requirements for the numbers of semaphores and large semaphore value
changes has greatly diminished, or there is a need to prevent large numbers
of semaphores or large value changes of a few 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.
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
semaem
was developed by AT&T.
SEE ALSO
sema(5),
semmap(5),
semmni(5),
semmns(5),
semmnu(5),
semmsl(5),
semume(5),
semvmx(5),
sysv_hash_locks(5).
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