Method and apparatus for hybrid packet-switched and circuit-switched flow control in a computer system

Abstract

A dynamically reconfigurable hybrid computer system is provided that executes transaction requests in one of two ways--either as packet-switched transactions or as circuit-switched transactions. Each transaction request is inspected as it is issued by a master device in the system, and it is determined in each case whether the transaction should be executed as a packet-switched transaction or as a circuit-switched transaction. Preferably, all slave read requests in a uniprocessor system are executed as circuit-switched transactions, such that a system controller coupled between the master device and the slave device, upon receipt of the request, immediately schedules the datapath between the master and slave devices and suspends other, competing transactions to execute the data transfer. The states of other transactions are stored, and are restored upon completion of the circuit-switched transaction. Criteria for determining whether a given transaction request should be treated as circuit-switched include: the type of transaction requests (e.g. all slave read requests may be treated as circuit-switched); whether the system includes only one or alternatively multiple processors (e.g., all slave read requests in a uniprocessor system may be treated as circuit-switched while those in a multiprocessor system may be treated as packet-switched); the destination address of the slave device for which the transaction request is intended (e.g. read requests to fast devices such as PCI devices may be treated as circuit-switched); and the identity of the master issuing the request. The system is dynamically reconfigurable, by specifying different criteria in software and/or by automatically determining, upon insertion or removal (or malfunctioning) of a processor, that the system should operate in a uniprocessor mode or a multiprocessor mode, where the criteria are at least in part different in the two modes.

Dependencies are inferred from the claim text.