hpux man page for msgmbs

msgmbs(5)							File Formats Manual							 msgmbs(5)

NAME
       msgmbs - maximum number of megabytes for all System V IPC message queues

VALUES
   Default
   Failsafe
   Allowed Values
DESCRIPTION
       The tunable specifies the maximum allowable total combined size, in megabytes, of all System V IPC messages in the system at any one time.

       If  a system call attempts to exceed the limit imposed by it will block (or return if was specified) until a caller of decreases the number
       of queued message bytes sufficiently such that the new message, along with other messages still on the queue, will fit within the limit.

       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.  Changes affect subsequent operations.

   When Should the Value of This Tunable Be Raised?
       Raise this tunable if applications have a need to store more data on a system.

   What are the Side Effects of Raising the Value?
       Raising this value increases the total message data which may be queued at any point in time.  This can result in having to block less fre-
       quently.

       Since message queue headers are stored in kernel memory, that memory is unavailable for use by other system services.

   When Should the Value of This Tunable Be Lowered?
       Lower this tunable when applications have no need to store large amounts of data on a single queue.

   What are the Side Effects of Lowering the Value?
       Lowering  the  tunable  value  has no effect on any active messages, even if the new tunable value is less than the total number of message
       bytes currently enqueued.  However, no new messages may be queued until the total number of bytes 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 tunables.

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
       msgrcv(2), msgsnd(2), mesg(5), msgmni(5), msgtql(5), msgmnb(5).

							     Tunable Kernel Parameters							 msgmbs(5)