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Aging Cached Shared Selectors before Reuse

IP.com Disclosure Number: IPCOM000108602D
Original Publication Date: 1992-Jun-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 2 page(s) / 67K

Publishing Venue

IBM

Related People

Cox, D: AUTHOR [+3]

Abstract

This article describes a method for aging selectors which are stored in a selector caching mechanism, such as that described in the preceding article, in order to protect the data being used within the memory segments. Caching shared selectors and reusing them is a good way to achieve performance gains in applications built to run on OS/2*. Over time, processes will gain access to many of the cached selectors and will not have to re-access the selectors when used later for another purpose. This improves overall OfficeVision*/2 (OV/2) performance.

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This is the abbreviated version, containing approximately 53% of the total text.

Aging Cached Shared Selectors before Reuse

       This article describes a method for aging selectors which
are stored in a selector caching mechanism, such as that described in
the preceding article, in order to protect the data being used within
the memory segments.  Caching shared selectors and reusing them is a
good way to achieve performance gains in applications built to run on
OS/2*. Over time, processes will gain access to  many of the cached
selectors and will not have to re-access the selectors when used
later for another purpose.  This improves overall OfficeVision*/2
(OV/2) performance.

      However, this also presents a problem if an application is
"misbehaving" with its use of shared memory.  When a shared selector
is placed in the "free" Cache control table, it is immediately
available for reuse.  Processes which have been working with this
shared memory do not lose access to it, and could therefore
inadvertently continue to alter it.

      In order to overcome this and other related memory problems in
our application systems, OV/2 Office built a Memory Management
subsystem, providing a layer of independence between applications
programs and the OS/2 operating system.  This subsystem is described
in (*). Using this Memory Management subsystem as the base, the
subsystem was enhanced to keep a cache list of segments allocated and
"in-use", and segments which are "free" and available for reuse.  One
cache list exists for all shared segment...