Method and system of aligning execution point of duplicate...

Details Method and system of aligning execution point of duplicate... Method and system of aligning execution point of duplicate...

2005-01-25

2008-12-16

McCarthy, Christopher S (Department: 2113)

Error detection/correction and fault detection/recovery

Data processing system error or fault handling

Reliability and availability

C712S204000, C712S209000

Reexamination Certificate

active

07467327

ABSTRACT:
A method and system of aligning execution point of duplicate copies of a user program by exchanging information about instructions executed. At least some of the exemplary embodiments may be a method comprising operating duplicate copies of a user program in a first and second processor, allowing at least one of the user programs to execute until retired instruction counter values in each processor are substantially the same, and then executing a number of instructions of each user program. Of the instructions executed, at least some of the instructions are decoded and the inputs of each decoded instruction determined (the decoding substantially simultaneously with executing in each processor). The method further comprises exchanging among the processors addresses of decoded instructions and values indicative of inputs of the decoded instructions, determining that an execution point of the user program in the first processor lags with respect to an execution point of the user program in the second processor using at least the addresses of the decoded instructions, and advancing the first processor until the execution point within each user program is substantially aligned.

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