HP-UX Reference (11i v3 07/02) - 5 Miscellaneous Topics (vol 9)

t
tcphashsz(5) tcphashsz(5)
(Tunable Kernel Parameters)
NAME
tcphashsz - determines the size of the networking hash tables
VALUES
Failsafe
2048
Default
2048
Allowed values
256 to 65536
Recommended values
2048
Specify as a power of two or it will be rounded down to the nearest power of two.
DESCRIPTION
This variable is used to set the size of the networking hash tables. A system that is going to have a large
number of connections on it all of the time may see some benefit of increasing this value.
This tunable needs to be a power of two. If it is not specified as a power of two, then it is rounded down to
the nearest power of two.
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?
This value may be raised in the case of a machine with a large number of connections that last for an
extended period of time.
What Are the Side Effects of Raising the Value?
More memory is used when this value is raised.
When Should the Value of This Tunable Be Lowered?
If a system is tight on memory and it has just a few connections on it, then lowering the value may reclaim
some memory.
What Are the Side Effects of Lowering the Value?
If set too low, the system will have long hash chains which will slow it down.
What Other Tunables Should Be Changed at the Same Time?
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://docs.hp.com.
AUTHOR
tcphashsz was developed by HP.
510 Hewlett-Packard Company − 1 − HP-UX 11i Version 3: February 2007