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Address Space Suballocation in a Virtual Storage Environment

IP.com Disclosure Number: IPCOM000080239D
Original Publication Date: 1973-Nov-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 5 page(s) / 47K

Publishing Venue

IBM

Related People

Jenner, EH: AUTHOR [+3]

Abstract

Data Base/Data Communication (DB/DC) Systems designed to interface between an operating system and problem solving application programs frequently perform address space suballocation and data area contents management functions, in controlling their own dynamically changing processing environments. In the interest of performance, both in its own area of processing responsibility, and across all concurrent processing activity, a DB/DC system, operating in a virtual storage environment must control its own dynamically dispensed storage area, in a manner consistent with the paging algorithm employed by the operating system. Described is a Storage Management facility designed to minimize contention, and to effect mutual cooperation between the DB/DC System and a Virtual Storage Operating System.

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Address Space Suballocation in a Virtual Storage Environment

Data Base/Data Communication (DB/DC) Systems designed to interface between an operating system and problem solving application programs frequently perform address space suballocation and data area contents management functions, in controlling their own dynamically changing processing environments. In the interest of performance, both in its own area of processing responsibility, and across all concurrent processing activity, a DB/DC system, operating in a virtual storage environment must control its own dynamically dispensed storage area, in a manner consistent with the paging algorithm employed by the operating system. Described is a Storage Management facility designed to minimize contention, and to effect mutual cooperation between the DB/DC System and a Virtual Storage Operating System.

In a virtual operating environment, the total size of the dynamic storage area managed by the DB/DC System has no effect on real storage utilization, since it occupies no real storage until it is suballocated and used to contain something. What does affect real storage utilization, is the density of interdependent or related suballocated address spaces within the pages in the dynamic storage area.

The Storage Management facility described categorizes its dynamically dispensed storage areas into multiple groups or subpools, based on common "content" or "intended-use" characteristics. By applying different page and subpool allocation algorithms, each designed to control and limit the directional growth of the subpool, an interactive effect is produced which is both performance oriented and efficient in its use of real storage. The Storage Management Module.

The Storage Management module manages its dynamic storage area in page size units, assigning pages to subpools as needed. Each subpool in turn manages its assigned pages, suballocating the address space, accounting for reusable space, and releasing pages as contiguous space is reacquired. The requests for storage include "intended-use" or "content" codes used by the Storage Management module in making the subpool selection.

Operating system paging algorithms distinguish between pages whose contents are merely referenced, and those whose contents are changed, bypassing redundant page-outs of "referenced-only" pages. Since, typically, programs are referenced and data areas are changed, separating them is consistent with the operating system paging algorithm.

The above diagram of dynamic storages gives an overview of how the total area is managed and how allocations are made. Content types considered to be data areas are allocated from lower addresses in an upward direction. Dynamically loaded programs' and tables' content spaces are allocated from the higher addresses of dynamic storage in a downward direction. The unallocated space between these allocated areas is also managed. As a page pool, it tends to move freely in the address sp...