fcache_async_cache_invalidate(5)fcache_async_cache_invalidate(5)NAMEfcache_async_cache_invalidate - toggle the deferred freeing of cached
The tunable is used to toggle the deferred freeing of cached pages. By
default, this tunable is set to 1; in other words. it is turned ON, and
the freeing of cached pages is deferred.
When this tunable is set to a value of 1, the system will try to asyn‐
chronously free pages from the cache that are in use by files that are
being removed via the rm(1) command, or those pages that are in cache
that are being used by the file systems and are being released via the
When this tunable is set to a value of 0, the system will free such
pages from the cache synchronously.
Who Is Expected to Change This Tunable?
Administrators investigating the performance characteristics of file
I/O intensive workloads.
Restrictions on Changing
Changes to this tunable take effect immediately.
When Should the Value of This Tunable be changed?
Leaving this tunable at its default value of 1 improves performance in
work loads where large amounts of files are being removed regularly, or
in cases where file systems are being unmounted. However, setting this
value to 1 leaves the free pages in such a state as to cause them to
exist as smaller contiguous chunks.
Applications starting up after an rm(1) or a umount(1) operation may
use up smaller translations and incur a higher TLB miss penalty, espe‐
cially if the pages just released represent a sizable portion of the
free memory in the system.
Change this tunable value to 0 only if there appears to be an adverse
impact on application startup times, and if performance in paths where
pages are being freed back to the system are not of much concern.
What Other Tunable Values Should Be Changed at the Same Time?
An invalid value is entered that is not an integer and is not 0 or 1,
such as a negative number.
All HP-UX kernel tunable parameters are release specific. This parame‐
ter may be removed or have its meaning changed in future releases of
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
was developed by HP.
Tunable Kernel Parafcache_async_cache_invalidate(5)