System Tunable Mapping: Tru64 UNIX to HP-UX 11i v2

The following table shows the system tuning options for System V IPC message queue attributes:
Tru64 UNIX HP-UX Dynamic on HP-UX Description
msg_max msgmax
Yes Maximum message size in bytes.
msg_mnb msgmnb
Yes Maximum message queue size in bytes.
msg_tql msgtql
No Maximum number of messages in the
system at any time.
msg_mni msgmni
No Maximum number of systemwide message
queues (IDs) allowed.
msg_max (Tru64 UNIX) versus msgmax (HP-UX)
This parameter defines the maximum allowable size, in bytes, of individual messages in a queue.
On Tru64 UNIX systems, increase the value of msgmax only if the applications being used on the
system require larger messages. This parameter prevents malicious or poorly written programs from
consuming excessive message buffer space.
The default value of this parameter is the same for Tru64 UNIX and HP-UX. However, the maximum
value allowed for this parameter is higher for Tru64 UNIX than HP-UX. The maximum value for Tru64
UNIX is INT_MAX; the maximum value for HP-UX is (
64*1024*1024), (msgssz*msgseg), or
msgmnb, whichever is smaller.
The msgssz tunable does not exist on Tru64 UNIX. On HP-UX, it specifies the size, in bytes, of a
“segment” of memory space reserved for storing IPC messages.
msg_mnb (Tru64 UNIX) versus msgmnb (HP-UX)
This parameter specifies the maximum total combined size, in bytes, of all the messages queued in a
given message queue at any one time.
The default value of this parameter is the same for Tru64 UNIX and HP-UX. However, the maximum
value allowed for this parameter is higher for Tru64 UNIX than HP-UX. The maximum value for Tru64
UNIX is INT_MAX; the maximum value for HP-UX is (
64*1024*1024) or (msgssz*msgseg),
whichever is smaller.
The msgseg tunable does not exist on Tru64 UNIX. On HP-UX, it specifies the total number of
“segments” of systemwide shared memory message storage space that is shared among all IPC
message queues.
msg_tql (Tru64 UNIX) versus msgtql (HP-UX)
This parameter specifies the maximum number of messages that are allowed to exist on the system at
any given time.
The default value of this parameter is different for Tru64 UNIX and HP-UX. The default setting is 40 for
Tru64 UNIX, and 1024 for HP-UX. The maximum value allowed for this parameter is different on
Tru64 UNIX and HP-UX. The maximum value for Tru64 UNIX is INT_MAX; the maximum value for
HP-UX is msgseg.
The msgmap tunable does not exist on Tru64 UNIX. On HP-UX it specifies the size of (number of
entries in) the message space resource map that tracks the free space in shared IPC message space.
The recommended value for this tuanble is msgtql+2.
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