hpux man page for pfdat_hash_locks

Query: pfdat_hash_locks

OS: hpux

Section: 5

Format: Original Unix Latex Style Formatted with HTML and a Horizontal Scroll Bar

pfdat_hash_locks(5)						     OBSOLETE						       pfdat_hash_locks(5)

NAME
pfdat_hash_locks - OBSOLETE kernel tunable parameter
DESCRIPTION
The tunable is obsolete and has been removed. HP-UX will automatically calculate the value based on the system configuration. Global kernel structures containing information on a running process or memory usage are frequently accessed or modified by several threads concurrently. To prevent race conditions, these structures are protected by spinlocks (kernel data used for synchronization) which allow only the spinlock "holder" to proceed, while all others attempting to access the structure must wait. Hashed spinlocks are used when each instance of such a data structure is to be protected, and there are several instances. Using a single spinlock for all instances would cause too much contention, but using one spinlock per structure wastes memory while the majority of the locks are unused at any given time. By allocating a pool of hashed locks, a hash function picks one lock per group of structures, reducing contention while conserving memory. The system-calculated value of sets the size of such a pool for the pfdat data structure spinlocks.
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. Tunable Kernel Parameters pfdat_hash_locks(5)
Related Man Pages
nstrevent(5) - hpux
allocate_fs_swapmap(5) - hpux
dma32_pool_size(5) - hpux
dlpi_max_clones(5) - hpux
pfdat_hash_locks(5) - hpux
Similar Topics in the Unix Linux Community
Max_io_size
Sux data structures 0.3 (Default branch)
Adding new kernel parameters
SpinLocks usage example
How major software is protected?