kmem_aggressive_caching man page on HP-UX

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kmem_aggressive_caching(5)			    kmem_aggressive_caching(5)

NAME
       kmem_aggressive_caching	-  policy  hint for caching and pre-allocating
       pages underlying the kernel dynamic memory

VALUES
   Failsafe
   Default
   Allowed values
DESCRIPTION
       The tunable provides a policy hint for favoring performance of  kernel-
       intensive  workloads,  by  caching  and	pre-allocating	physical pages
       underlying the kernel dynamic memory.

       must be a positive integer between 0 and 10, 0 being the default.

       In general, the kernel aggressively allocates large  pages  for	higher
       values  of  A change in the value may have a direct impact on number of
       physical pages allocated for use by kernel objects.

       If the kernel is not aggressive in using large pages for	 its  objects,
       then  kernel intensive workloads may witness numerous TLB misses during
       execution.  If the kernel is too aggressive, the system could  sometime
       encounter  a  brief shortage of free physical memory, which could delay
       application startup or cause page fault.

       On production systems, customers must evaluate the  performance	impact
       on their workload environment before changing the value of this tunable
       from the default value.	To determine a reasonable value for you should
       consider	 the  nature of the workload. A higher value may be useful for
       those workloads that are highly kernel-intensive.

   Who Is Expected to Change This Tunable?
       Administrators investigating the performance characteristics of	kernel
       intensive workloads.

   Restrictions on Changing
       Changes	to  this tunable take effect immediately; however, the changes
       would be effective only on new kernel memory allocations.

   When Should the Value of This Tunable Be Raised?
       The tunable should be raised when the system suffers from numerous  TLB
       misses  while  running  kernel  intensive workloads. In most cases, the
       default value should be sufficient.

   What are the Side Effects of Raising the Value?
       Increasing the value would increase the number of pages	allocated  for
       caching kernel objects.

   When Should the Value of This Tunable Be Lowered?
       The tunable should be lowered when applications suffer from delays dur‐
       ing startup or page fault due to lack of free memory.

   What are the Side Effects of Lowering the Value?
       Certain workloads may incur more TLB misses.

   What Other Tunable Values Should Be Changed at the Same Time?
       None

ERRORS
       An invalid value is entered that is not an integer
		      between 0 and 10, such as a negative number.

WARNINGS
       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 HP-UX Release Notes at

AUTHOR
       was developed by HP.

SEE ALSO
       fcache_vhand_ctl(5), filecache_min(5), filecache_max(5).

			   Tunable Kernel Parameterskmem_aggressive_caching(5)
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