msgtql(5)							File Formats Manual							 msgtql(5)

NAME

       msgtql - maximum number of System V IPC messages in the system at any time

VALUES

   Default
   Failsafe
   Allowed values
   Recommended values
       The largest number of messages expected.

DESCRIPTION

       The  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

       Note that if a system call attempts to exceed the limit imposed by it will block until message space becomes available or return if is set.

       Other kernel tunables may limit the maximum number of messages supported.  Limiting factors can be the maximum number of bytes in a  queue,
       and the maximum allowable total combined size, in bytes, in the system.

       For more information about System V message queues, refer to the section of the mesg(5) manpage.

   Who Is Expected to Change This Tunable?
       Anyone.

   Restrictions on Changing
       This tunable is dynamic.  Changes to to this tunable take effect immediately.

   When Should the Value of This Tunable Be Raised?
       Raise this tunable if applications block too frequently in requiring more total messages be held in the kernel message queues.

   What are the Side Effects of Raising the Value?
       Raising this value increases the possible number of messages which may be queued at any point in time.  This can result in msgsnd(2) having
       to block less frequently.  Since message queue headers are stored in kernel memory, that memory is unavailable for use by other system ser-
       vices.

   When Should the Value of This Tunable Be Lowered?
       Lower this tunable when applications no longer require as many total messages.

   What are the Side Effects of Lowering the Value?
       Lowering  the  value  increases	the  risk  of application failure due to the inability to send more messages.  Lowering the tunable has no
       effect on any queued messages, even if the new tunable value is less than the number of queued messages.  However, no new messages  may	be
       queued until the number of messages falls below the setting of

   What Other Tunable Values Should Be Changed at the Same Time?
       All  the  System  V message queue tunables are interrelated and should be treated as independent variables.  The set must be evaluated as a
       system to ensure the tunables reflect the application requirements.  The message tunables include and Specifically, the	and  tunables  may
       need to be adjusted along with the 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.

       System resource limits (such as, memory) may limit the number and/or total size of queued messages. These system limits may be  encountered
       before the limit values of the msgtql and msgmbs tunables.

       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  tun-
       able  values,  consult  the documentation for the kernel software being installed.  For information about optional kernel software that was
       factory installed on your system, see at

AUTHOR

       was developed by AT&T.

SEE ALSO

       msgsnd(2), mesg(5), msgmnb(5), msgmni(5), msgmbs(5).

							     Tunable Kernel Parameters							 msgtql(5)