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Verification Query Rollback Versus Causality Rollback

Verification query  rollbacks are the most critical part of the predictive management system. They are handled in a slightly different fashion from causality  failure rollbacks. A state verification failure causes the LP state to be corrected at the time of the state verification which failed. The state, tex2html_wrap_inline850 , has been obtained from the actual device from the verification query at time tex2html_wrap_inline852 . The LP rolls back to exactly tex2html_wrap_inline852 with state, tex2html_wrap_inline850 . States greater than tex2html_wrap_inline852 are removed from the state queue . Anti-messages  are sent from the output message queue for all messages greater than tex2html_wrap_inline852 . The LP continues forward execution from this point. Note that this implies that the message and state queues cannot be purged of elements which are older than the GVT. Only elements which are older than real time can be purged.



Steve Bush
Thu Feb 27 15:34:42 CST 1997