Browse Prior Art Database

Sharing Processor Memory among Multiple Virtual Pages

IP.com Disclosure Number: IPCOM000118757D
Original Publication Date: 1997-Jun-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 73K

Publishing Venue

IBM

Related People

Rubsam, KG: AUTHOR [+2]

Abstract

Disclosed is a technique for solving the problem of duplicating data and code by sharing the computer memory (real/main storage) with multiple virtual storage addresses at a page granularity. This is accomplished by managing the operating system's page tables for virtual storage so that more than one virtual page can be backed by the same real frame. This concept will be referred to as "Captured Storage". Captured Storage may be defined both statically and dynamically. That is, relationships between virtual structures could be defined essentially at Initial Program Load (IPL) time or at time of use. Dynamic Captures could be deleted essentially at any time.

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This is the abbreviated version, containing approximately 52% of the total text.

Sharing Processor Memory among Multiple Virtual Pages

      Disclosed is a technique for solving the problem of duplicating
data and code by sharing the computer memory (real/main storage) with
multiple virtual storage addresses at a page granularity.  This is
accomplished by managing the operating system's page tables for
virtual storage so that more than one virtual page can be backed by
the same real frame.  This concept will be referred to as "Captured
Storage".  Captured Storage may be defined both statically and
dynamically.  That is, relationships between virtual structures could
be defined essentially at Initial Program Load (IPL) time or at time
of use.  Dynamic Captures could be deleted essentially at any time.
In Multiple Virtual Storage/Enterprise Systems Architecture (MVS/ESA)
terms, Capture relationships could be between address spaces, between
one or more address spaces to a data space or between virtual
addresses within an address space.

      A relationship between two or more virtual storage ranges is
established using a mapping structure along with page table entries
for each of the virtual ranges which will use the same real frames.
Note that the granularity of the Capture could be as small as a
single page  or could encompass a wide range of pages.  Note further
that the solution  does not dictate that the virtual addresses in
each of the Captured ranges must be the same.  The virtual addresses
could be the same, but  they need not be.  This design permits a page
in a virtual space to be  in Capture mode with one or more pages in
other virtual spaces.

      More than one implementation of the disclosure are possible,
but the one outlined here seems to have the greatest number of
advantages and the fewest disadvantages.

      The primary linkage mechanism between the virtual pages is the
Page Locator Block (PLB).  One PLB will be created for every virtual
page that is in Capture mode.  The PLBs reside in...