Unisys Corporation

Robert C Gulick

Douglas E Morrissey

Mitchell A Bauman

Charles R Caldarale

Hans Christian Mikkelsen

Craig F Russ

James R Hunter

Sharon M Mauer

Maureen P Connell

Bruce Alan Vessey

Eugene W Troxell

A computer system comprises a plurality of processing modules that can be configured into different partitions within the computer system, and a main memory. Each partition operates under the control of a separate operating system. At least one shared memory window is defined within the main memory to which multiple partitions have shared access, and each partition may also be assigned an exclusive memory window. Program code executing on different partitions enables those partitions to communicate with each other through the shared memory window. Means are also provided for mapping the physical address space of the processors in each partition to the respective exclusive memory windows assigned to each partition, so that the exclusive memory windows assigned to each partition appear to the respective operating systems executing on those partitions as if they all start at the same base address.

Computer system and method for operating multiple operating systems in different partitions of the computer system and for allowing the different partitions to communicate with one another through shared memory

System and method for controlling the flow of messages in a computer system to minimize congestion and prevent deadlocks in communications. The computer system includes a main memory, a plurality of crossbar switches, a plurality of third level caches, and a plurality of input/output modules, which are interconnected via the communications network of the computer system. System and method prevents deadlocks between input/output modules and main memory, and between processors and main memory caused by data needed for making forward progress in processing being trapped behind messages. System and method utilize control signals and auxiliary buffers to hold and redirect messages out of the path of data so that data may flow to the input/output modules and processors when needed, and messages may flow when convenient.

Message flow protocol for avoiding deadlocks

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Glenmoore, PA, United States of America

Robert C Gulick