|
|
HP-UX Reference > Ddnlc_hash_locks(5)Tunable Kernel ParametersHP-UX 11i Version 2: December 2007 Update |
|
NAMEdnlc_hash_locks — number of locks for the Directory Name Lookup Cache (DNLC) DESCRIPTIONTo speed up the search through directories in the kernel, there is a memory resident cache of directories called the Directory Name Lookup Cache (DNLC). During a filename lookup in the kernel, any directories or files encountered are retained in the DNLC for future reference. The DLNC is managed in a Least Recently Used (LRU) fashion. The dnlc_hash_locks dictates the number of lock groups that will be used to manage the directory entries in the DNLC hash chains. Restrictions on ChangingThis 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 reduce lock contention and 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 to allocate locks for the DNLC. When Should the Value of This Tunable Be Lowered?The value can be lowered to limit the number of locks allocated for the DNLC and reduce memory consumption. What are the Side Effects of Lowering the Value?Less system memory will be consumed for the DNLC locks upon system reboot. Operations requiring filename lookup (for example, open(2)) may experience performance degradation. WARNINGSAll 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 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. |
|