NAME
msgtql — maximum number of System V IPC messages in the system at any time
VALUES
Allowed values
Minimum: 1
Maximum: msgseg
Recommended values
The largest number of messages expected.
DESCRIPTION
The
msgtql
tunable specifies the maximum total system-wide individual messages
across all message queues.
Every message has a header to specify message type and location
and the total number of headers is limited by
msgtql.
Note that if a
msgsnd()
system call attempts to exceed the limit imposed by
msgtql,
it will block until message space becomes available or return
EAGAIN
if
IPC_NOWAIT
is set.
For more information about System V message queues, refer to the
"Overview" section of the
mesg(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?
Raise this tunable if applications block too frequently in
msgsnd(),
requiring more total messages be held in the kernel message queues.
When Should the Value of This Tunable Be Lowered?
Lower this tunable when applications no longer require as many total messages.
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 variables.
The set must be evaluated as a system to ensure the tunables reflect
the application requirements.
The
mesg
tunables include
msgmap,
msgmax,
msgmnb,
msgmni,
msgseg,
msgssz,
and
msgtql.
Specifically, the
msgseg
or
msgssz
tunables may need to be adjusted along with the
msgtql
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
msgtql
was developed by AT&T.
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