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allocate_fs_swapmap(5)					allocate_fs_swapmap(5)

NAME
       allocate_fs_swapmap  - determines when swapmap structures are allocated
       for filesystem swap

VALUES
   Failsafe
   Default
   Allowed values
       or

DESCRIPTION
       The tunable is  used  to	 determine  whether  to	 allocate  all	needed
       filesystem  swap structures during the initialization of the filesystem
       swap device or wait until  they	are  needed.   Pre-allocation  of  all
       filesystem  swap structures upon initialization saves time during later
       usage of the filesystem swap, and prevents later allocation failure due
       to physical memory contention.

       Dynamic	allocation  decreases  the  memory footprint of the filesystem
       swap system.

   Who is Expected to Change This Tunable?
       Anyone.

   Restrictions on Changing
       Changes to this tunable take effect at the next reboot.

   When Should the Value of This Tunable Be Raised?
       Systems under heavy memory load may not be able to acquire enough  mem‐
       ory  to hold the swap mapping structures for an addition of file system
       swap.  These calls to add swap would fail with the error though presum‐
       ably they would be retried.  Frequent failure on file system swap addi‐
       tion with would merit enabling this tunable.

   What Are the Side Effects of Raising the Value?
       All the swap map structures for each file system swap device  would  be
       preallocated  during swap initialization at kernel boot, increasing the
       memory footprint of the kernel.	The amount of increase depends on  the
       number and size of file system swap devices.

   When Should the Value of This Tunable Be Lowered?
       Systems with limited memory available to the kernel that also have lim‐
       ited use of file system swap devices should  disable  this  tunable  to
       decrease kernel memory usage.

   What Are the Side Effects of Lowering the Value?
       File  system  swap  additions  may  fail with when memory contention is
       high.

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

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 at

AUTHOR
       was developed by HP.

			   Tunable Kernel Parameters	allocate_fs_swapmap(5)

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