Amdahl Corporation

Stephen C Magee

Peter H Lipman

Jeffrey L Baker

Ronald N Hilton

A multiprocessor (MP) computer sytem which allows target CPU(s) to continue processing instructions while other target CPU(s) are processing instructions of emulation code to reach their end of a Domain Unit of Operation before synchronization. A two-level MP sync is used since the target CPUs must be in between units of operation when the updates occur since a unit of operation can be one instruction or it can be many instructions that together emulate one instruction. Two level MP sync allows CPUs that are going to be serialized to continue to process single instructions (no emulation code) while other target CPUs are in emulation mode.

Apparatus and method for controlling the initiating of a synchronization

A storage unit for a data processing system includes a cache data buffer, a cache tag, and a translation lookaside buffer (TLB). Storage keys are maintained in the TLB with a separate valid bit, which allows a valid translation to be stored upon completion of a translation, even though the key is not yet available. With a valid translation in the TLB entry available, the requesting port is then able to send off a move in request to mainstore right away in parallel with a key request from the translator to the mainstore key array. In the typical case, the key will be returned several cycles ahead of the data, allowing it to be written into the TLB entry and validated in time for the move in data to be successfully bypassed to the requestor as soon as it arrives.

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San Jose, CA, United States of America

Stephen C Magee