International Business Machines Corporation

Donald Ingerman

Thomas Basilio Genduso

Robert Andrew Lackman

Richard Allen Kelley

Shah Mohammad Rezaul Islam

Edward Robert Vanderslice

A method and system in a data processing system for dynamically scheduling the processing of a plurality of requests to access a disk, in which each of the plurality of requests is associated with a location on the disk, processes the requests in a first sequential order and determines the amount of time necessary to process a selected number of requests associated with locations between the current location on the disk and the most urgent request. At a time that is earlier than the deadline for processing the most urgent request by the amount of time necessary to process the selected number of requests, the method commences processing of the selected number of requests in a second sequential order.

Method of and system for the dynamic scheduling of requests to access a storage system

A method and system in data processing system are disclosed for efficiently servicing requests to access a disk. Each of the requests are associated with a location on the disk. The requests include real-time requests and non-real time requests. A most urgent one of the requests is determined. The most urgent one of the requests is associated with a first deadline and a first location on the disk. A second most urgent one of the requests is also determined. The second most urgent one of the requests is associated with a second deadline and a second location on the disk. The first deadline is earlier in time than the second deadline. A service time is determined. The service time is earlier in time than the first deadline. The service time is determined so that sufficient time will exist to service the most urgent one of the requests before the first deadline and service the second most urgent one of the requests before the second deadline. A closest request is determined by determining whether the first location or the second location is closest to a current location of a disk arm. The closest request is either the most urgent one of the requests or the second most urgent one of the requests. In response to a current time reaching the service time, the closest request is serviced such that the most urgent one of the requests is serviced before the first deadline and the second most urgent one of the requests is serviced before the second deadline.

Data processing system and method for efficiently servicing pending requests to access a storage system

A method and system in data processing system are disclosed for the dynamic scheduling of a plurality of requests to access a disk. Each of the requests is associated with a location on the said disk which each of the requests is attempting to access. A scan queue is established for storing the plurality of requests. The plurality of requests are processed in a sequential order. The sequential order is determined utilizing the location on the disk being accessed by each of the requests. Upon one of the stored requests being urgent, the urgent request is processed. The urgent request is associated with a first location on said disk. Processing of the requests then continues in a second sequential order. The second sequential order is determined utilizing the first location. The next request to be processed is one of the requests which is associated with a physically closest location on the disk.

Method and system for the dynamic scheduling of requests to access a storage system

Data is transferred over a bus from one device to another, or between one device and another system resource, such as a central processor. This data is classified into one of several types. 'Hard real time' data must be transferred within a specified time limit or 'deadline' and it is unacceptable to miss a deadline. 'Soft real time' data should be transferred before a deadline and, although some missed deadlines are tolerable, the lower the number of missed deadline the better. 'Loss sensitive' data has no deadlines, but any loss of data is unacceptable. 'Non-real time' data also has no deadlines, but the lower the time delay in transferring the data the better. The intelligence that controls the transfer of data and schedules access to the bus is distributed throughout the system. Part of this scheduling intelligence is included in the bus arbiter, while the remainder is incorporated in the devices themselves.

Distributed scheduling for the transfer of real time, loss sensitive and

A multi-processor information handling system employs multiple multi-processor bus/memory subsystem groups wherein the processors may operate programs concurrently, and concurrent memory operations may be performed with the multiple memory subsystems via the associated multi-processor buses responsive to address location directors. The invention expands the system bandwidth and improves overall multi-processor information handling system performance.

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Raleigh, NC, United States of America

Donald Ingerman