International Business Machines Corporation

Robert Andrew Lackman

Thomas Basilio Genduso

Donald Ingerman

Richard Allen Kelley

Shah Mohammad Rezaul Islam

Edward Robert Vanderslice

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

A method and system provide end-to-end flow control between a sender and a receiver attached to a network. The data is divided into a plurality of packets. A priority hierarchy of a plurality of priority levels is established. Each packet of data is associated with one of the priority levels. Transmission of the plurality of packets is initiated from a transmitter to a receiver transmitting the plurality of packets in the priority hierarchy. The real-time data is divided into a plurality of frames. Each of the plurality of frame is divided into multiple packets. Each of the plurality of frames is stored in a frame buffer included within the receiver. During transmission, a level of a plurality of frames included within the frame buffer is monitored. In response to the level crossing a first buffer threshold, a determination is made as to whether a first plurality of the multiple packets are associated with a first priority level. In response, the priority level associated with the first plurality of the multiple packets is then modified to be a second priority level. Transmission is then continued where the first plurality of the multiple packets are transmitted utilizing only the second priority level.

Method and system in a data processing system for dynamically controlling transmission of data over a network for end-to-end device flow control

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.

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Wake Forest, NC, United States of America

Robert Andrew Lackman