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Time Warp Emulation

The motivation behind TWE is to allow a real-time system to work ahead in time by predicting future behaviour and adjusting itself when that behaviour does not match reality. This is accomplished by realizing that there are now two types of false messages, those which arrive in the past relative to the process's Local Virtual Time (LVT) and those messages which have been generated which are timestamped with the current real time, but whose values exceed some tolerance from the actual value.

Here the basic Time Warp mechanism is modified by adding a verification query phase. This phase occurs when real time matches the receive time of a message in the output queue of a process. In this phase the physical device being emulated is queried and the results compared with the value of the message. A value exceeding a prespecified tolerance will cause a rollback of the process.



Steve Bush
Mon Aug 26 18:24:40 CDT 1996