nflocks(5)nflocks(5)NAMEnflocks - maximum number of file locks
VALUES
Failsafe
Default
The default value is computed at runtime and depends on the amount of
physical memory on the system. For small memory systems (less than
1GB), the default is 1200. For systems with more than 1GB of memory,
the default is 4096, or 4K.
Allowed values
The minimum value is 50. The maximum value is 0x1000000.
Specify a positive integer value.
DESCRIPTION
The tunable represents the maximum number of file locks that are avail‐
able system-wide.
Who Is Expected to Change This Tunable?
This tunable should be changed on systems expected to run applications
with large number of file locks. When changing this number note that
one file may have several locks, and databases that use or may need an
exceptionally large number of locks.
Restrictions on Changing
This tunable is dynamic (tuning will take effect immediately on the
running system). When the value of is dynamically tuned it cannot be
set to a value lower than the current number of file locks in the run‐
ning kernel.
When Should the Value of This Tunable Be Raised?
The value should be increased when large numbers of file locks are
expected to be used simultaneously.
What are the Side Effects of Raising the Value?
The kernel allocates a portion of memory proportional to the new value
of and frees memory proportional to the old value. Additional memory
is consumed as new locks are created.
When Should the Value of This Tunable Be Lowered?
The value can be lowered to limit the number of available file locks on
a system and reduce memory consumption.
What are the Side Effects of Lowering the Value?
The kernel allocates a portion of memory proportional to the new value
of and frees memory proportional to the old value. Additional memory
may be released to the system to be used for other purposes if the
usage was ever higher than this new value.
What Other Tunable Values Should Be Changed at the Same Time?
None.
WARNINGS
Setting to the maximum value (0x1000000) will result in a large memory
allocation (~.5GB). A request to change the value of will fail with
set if there is either not enough free memory or the remaining free
memory would be so small as to potentially hinder system performance.
All HP-UX kernel tunable parameters are release specific. This parame‐
ter 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 parameter values. After installation, some
tunable parameters may no longer be at the default or recommended val‐
ues. For information about the effects of installation on tunable val‐
ues, 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 HP.
SEE ALSOkctune(1M), sam(1M), gettune(2), settune(2), fcntl(2), lockf(2).
Tunable Kernel Parameters nflocks(5)
