nstrevent.5 (2010 09)

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NSTREVENT(5) NSTREVENT(5)
(Tunable Kernel Parameters)
NAME
NSTREVENT - maximum number of outstanding STREAMS bufcalls
VALUES
Failsafe
50
Default
50
Allowed values
0 - 2147483647
Recommended values
50
DESCRIPTION
This tunable limits the maximum number of outstanding
bufcalls that are allowed to exist in the sys-
tem at any given time.
This tunable is intended to protect the system against resource overload caused by the combination of
modules running in all streams issuing an excessive number of
bufcalls. The value selected should be
equal to or greater than the combined maximum number of bufcalls that can be reasonably expected
during normal operation from all streams on the system. bufcalls are used by STREAMS modules in
low memory situations.
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?
When the system has a lot of low memory situations.
What Are the Side Effects of Raising the Value of This Tunable?
If too big a number is chosen, the STREAMS subsystem preallocates more memory for internal data
structures than may be needed. This reduces the amount of memory available to applications and the
system.
When Should the Value of This Tunable Be Lowered?
If the tunable is increased for a particular STREAMS module/driver, this tunable can be lowered when
that STREAMS module/driver is removed. It should be returned to its previous value. However, HP does
not recommend a value lower than the default value.
What Are the Side Effects of Lowering the Value of This Tunable?
During low memory situations, it will bring down system performance.
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
NSTREVENT was developed by HP.
HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1