Browse Prior Art Database

Minimizing Duration of Resource Usage for Preplanned Resource Requests

IP.com Disclosure Number: IPCOM000074348D
Original Publication Date: 1971-Apr-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Auslander, MA: AUTHOR [+2]

Abstract

With multiprogrammed computer operating systems, some resource request situations require the passing of a resource between different program tasks. A deadlock can develop in which each of two tasks is waiting for a resource which the other is holding. Such deadlock may be avoided by the following described technique.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

Page 1 of 2

Minimizing Duration of Resource Usage for Preplanned Resource Requests

With multiprogrammed computer operating systems, some resource request situations require the passing of a resource between different program tasks. A deadlock can develop in which each of two tasks is waiting for a resource which the other is holding. Such deadlock may be avoided by the following described technique.

From advance knowledge provided by resource requests (such as may be made with job control language statements), a Resource Table (such as shown) may be constructed with rows representing resources, and columns representing times (such as job steps) at which resources may be requested/ released. Each position in the table contains a "zero" if the resource is not needed and is not to be passed, a "one" if the resource is needed and is not to be passed, and a "two" if the resource is to be passed to the next resource period, (i.e. job step). The input form of the table is labeled (BEFORE).

The (BEFORE) table is scanned from its second last column S(3) to its first column S(1). If all items in each column are "zero" or "one", the column represents a "resource break", which means that all resources may be released after use by that job step. If any item is a "two", then all resources which will be needed in the next resource period (i.e. next job step) must be "promoted" by being held for the next job step, since a resource may not be requested while others are held by this job step...