strmsgsz.5 (2010 09)

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STRMSGSZ(5) STRMSGSZ(5)
(Tunable Kernel Parameters)
NAME
STRMSGSZ - maximum size of streams message data (bytes)
VALUES
Failsafe
0
Default
0
Allowed values
0 - 2147483647
Recommended values
0
DESCRIPTION
This tunable limits the number of bytes of message data that can be inserted by
putmsg() or write()
in the data portion of any streams message on the system. If the tunable is set to zero, there is no limit
on how many bytes can be placed in the data segment of the message.
putmsg() returns [ERANGE] if the buffer being sent is larger than the current value of
STRMSGSZ;
write() segments the data into multiple messages.
Who Is Expected to Change This Tunable?
Any customer.
Restrictions on Changing
Changes to this tunable take effect at next reboot.
When Should the Value of This Tunable Be Raised?
The tunable should be increased by any customer if the customer’s STREAMS module/driver(s) require a
longer message size in the data portion than the current value.
What Are the Side Effects of Raising the Value of This Tunable?
The kernel will use more memory. During low memory situations, it may bring down system performance
due to frequent swapping.
When Should the Value of This Tunable Be Lowered?
The tunable could be lowered by any customer if the customer’s STREAMS module/driver(s) do not
require a longer message size in the data portion than the current value.
What Are the Side Effects of Lowering the Value of This Tunable?
Possible improper functioning in any of the STREAMS module/driver(s). Possible performance degrada-
tion, particularly in networking.
What Other Tunable Should Be Changed at the Same Time as This One?
None.
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.
Installation of optional kernel software, from HP or other vendors, may cause changes to tunable parame-
ter values. After installation, some tunable parameters may no longer be at the default or recommended
values. For information about the effects of installation on tunable values, consult the documentation for
the kernel software being installed. For information about optional kernel software that was factory
installed on your system, see HP-UX Release Notes at
http://www.hp.com/go/hpux-core-docs.
AUTHOR
STRMSGSZ was developed by HP.
HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1