Browse Prior Art Database

A Memory Dependent Swap File Allocation Heuristic

IP.com Disclosure Number: IPCOM000121200D
Original Publication Date: 1991-Jul-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 1 page(s) / 48K

Publishing Venue

IBM

Related People

Lanning, DL: AUTHOR [+3]

Abstract

Described is a technique for detecting when a computer operating system (OS) can satisfy virtual memory allocations while allocating swap file space.

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A Memory Dependent Swap File Allocation Heuristic

      Described is a technique for detecting when a computer
operating system (OS) can satisfy virtual memory allocations while
allocating swap file space.

      Previously an OS allocated enough space in the swap file to
accommodate the total amount of swappable overcommit.  In practice,
however, there are always swappable segments in memory.  Some portion
of the swap file goes unused.

      Some portion of the swappable overcommit is always resident in
memory.  The technique disclosed herein reduces the swap file
allocation by that amount.  At least half of the movable area is
available for swappable segments.

      It is now possible for a swap-out to fail due to lack of disk
space.  When this occurs, the memory request is satisfied by
discarding rather than swapping.  Swappable segments are skipped over
until the allocation is satisfied.

      The size of the swap file is reduced dramatically, especially
for large memory configuration personal computer systems.  The OS is
able to run more programs in a memory/disk-constrained machine.

      Disclosed anonymously