HP-UX Reference (11i v2 03/08) - 5 Miscellaneous Topics, 7 Device (Special) Files, 9 General Information, Index (vol 9)
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msgmni(5) msgmni(5)
(Tunable Kernel Parameters)
NAME
msgmni - maximum number of system-wide System V IPC message queues (IDs) allowed
VALUES
Default
512
Failsafe
512
Allowed Values
Minimum: 1
Maximum: 32767
DESCRIPTION
The msgmni tunable specifies the maximum number of system-wide System V IPC message queue
identifiers (one per queue). Each message queue created has an identifier (ID) and there is an upper
limit of msgmni identifiers.
Applications use the
msgget() system call to create new queues. If all IDs have been used,
msgget()
will return [ENOSPC].
If a process acquires a message queue, but the process terminates without removing it, the queue and all
its messages remain. Abandoned message queues can be removed with the
ipcrm command. Message
queue status can be monitored using the ipcs command.
For more information about System V message queues, refer to the Overview section of the mesg(5) man-
page.
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?
Raise this tunable when applications require more queues.
When Should the Value of This Tunable Be Lowered?
Lower this tunable when the requirement for queues has diminished.
What Other Tunable Values Should Be Changed at the Same Time?
All the System V message queue tunables are interrelated and should not be treated as independent vari-
ables. The set must be evaluated as a system to ensure the tunables reflect the application requirements.
The message tunables include
msgmap, msgmax, msgmnb, msgmni, msgseg, msgssz, and msgtql.
Specifically, the msgseg and msgtql tunables, may need adjustment along with changes to the msgmni
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.
AUTHOR
msgmni was developed by AT&T.
SEE ALSO
ipcrm(1), ipcs(1), msgget(2), mesg(5), msgmap(5), msgmax(5), msgmnb(5), msgseg(5), msgssz(5),
msgtql(5).
HP-UX 11i Version 2: August 2003 − 1 − Hewlett-Packard Company Section 5−−183