Hewlett-packard Company

Bernard L Stumpf

Barry J Flahive

Dale Calvin Morris

Stephen G Burger

Jeffrey D Kurtze

Richard G Bahr

Michael L Ziegler

William R Bryg

Jerome C Huck

Ruby B Lee

Hugh C Lauer

Stephen J Ciavaglia

Jeff Kurtze

Ruby B L Lee

George M Stabler

Mark Kline

A computer apparatus incorporating special instructions to force load and store operations to execute in program order. The present invention provides a new and novel store instruction that is suspended until all prior store instructions have been completed by an associated CPU. Also, a new load instruction is provided which blocks any subsequent load instructions from executing until this load instruction has been completed by an associated CPU. These instructions allow for high efficiency computer systems to be implemented which optimize instruction throughput by executing subsequent instructions while waiting for a prior instruction to complete.

Computer apparatus having special instructions to force ordered load and store operations

A computer apparatus which detects a store or load operation into or from a shared memory page by a program that does not provide for synchronization when executed by a CPU that completes instructions out of program order. After the store or load is detected, the CPU explicitly orders operations into the shared memory page. Store operations are ordered such that no new store into the shared memory page is performed until all prior store operations into the shared memory page are complete. Also, load operations are ordered such that load operations from the shared memory page are performed in program order. This ordering is achieved by maintaining a process bit and a memory attribute bit associated with a shared memory page. When both bits are true, all load or store operations referencing the shared memory page are ordered.

Computer that selectively forces ordered execution of store and load

A method for preserving data transfer order in a pipeline computer system, wherein a first block of data is transferred from a first device to at least a second device during a first computer cycle. Simultaneously, the first block of data is stored within the first device. Druing a second computer cycle, a second block of data is transferred from the first device to the second device, and an acknowledge signal is issued, indicating the success or failure of the transfer of the first block of data. If the acknowledge signal indicates a failed data transfer, a reject signal is issued and data transfer is restarted beginning with the previously failed data transaction which has been stored within the first device, and data transfer then continues with a preserved data transfer order.

Pipeline computer system having write order preservation

A computer system having a plurality of processors sharing common memory and data bus structures and operable to perform atomic operations which comprise several instruction actions, wherein the processor performing the atomic operation prevents memory access interruptions by other processors by locking out other processors during the atomic operation. The system bus includes signal paths accommodating bus lock request and bus lock signals which are provided and received by each processor, which signals are initiated by specific bus lock and lock release instructions added to each processor instruction set.

Method and apparatus for bus lock during atomic computer operations

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Chelmsford, MA, United States of America

Bernard L Stumpf