ncsize(5) File Formats Manual ncsize(5)
NAME
ncsize - number of Directory Name Lookup Cache (DNLC) entries
VALUES
Failsafe
Default
Allowed values
The minimum value allowed is The maximum value allowed is memory limited. The value is further constrained in that it must be equal to or
greater than eight times the value of the number of locks for the DNLC
Specify a positive integer value.
DESCRIPTION
To speed up the search through directories in the kernel, there is a memory resident cache of directories called the During a filename
lookup in the kernel, any directories or files encountered are retained in the DNLC for future reference. The tunable dictates the number
of entries in the DNLC, which is statically allocated at system boot time. Therefore, the larger the value of the larger the number of
directory/file entries that can be kept cached in memory for filename lookup.
Who Is Expected to Change This Tunable?
HP-UX system administrators.
Restrictions on Changing
This tunable is static. Any changes to the value of this tunable will require system reboot before taking effect.
When Should the Value of This Tunable Be Raised?
The value may need to be raised to improve filename lookup performance when running applications which require large numbers of filename
access.
What are the Side Effects of Raising the Value?
More system memory will be consumed for the DNLC.
When Should the Value of This Tunable Be Lowered?
The value can be lowered to limit the number of entries in the DNLC and reduce memory consumption.
What are the Side Effects of Lowering the Value?
Less system memory will be consumed for the DNLC upon system reboot. Operations requiring filename lookup (e.g. open(2)) may experience
performance degradation.
What Other Tunable Values Should Be Changed at the Same Time?
The value of must be equal to or greater than eight times the value of
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 parameter values. After installation,
some tunable parameters may no longer be at the default or recommended values. For information about the effects of installation on tun-
able values, 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 ALSO
kctune(1M), sam(1M), gettune(2), settune(2), dnlc_hash_locks(5).
Tunable Kernel Parameters ncsize(5)
