NAME
semvmx — maximum value of any single System V IPC semaphore
VALUES
Allowed values
Minimum: 1
Maximum: 65535
DESCRIPTION
The
semvmx
tunable specifies the maximum value any given System V IPC semaphore
can have.
If an application attempt to exceed this limit, it will receive an
ERANGE
error from
semop()
or from
semctl().
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 requires larger semaphore values.
When Should the Value of This Tunable Be Lowered?
If requirements for the single semaphore value has
decreased, or if there for limit protection on run-away applications which
change 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 semaphore tunables include
semaem,
semmni,
semmns,
semmnu,
semmsl,
semume,
semvmx,
and
sysv_hash_locks.
Consider changes to
semaem
when changing
semvmx.
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.
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
semvmx
was developed by AT&T.
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