Other recovery mechanisms
Checkpoint repair mechanism:
- The processor provides a set of logical spaces, where each logical space consists of a full set of software-visible registers and memory.
- One is used for current execution, the others contain back-up copies of the in-order state that corresponds to previous points in execution.
- At various times during execution, a check-point is made by copying the architectural state of the current logical state to the back-up space.
- Restarting is accomplished by loading the contents of the appropriate back-up stage into the current logical state.
- The (architectural) register file contains the current state, and the history buffer contains old register values which have been replaced by new values.
- The history buffer is managed as LIFO stack, and the old values are used to restore a previous state if necessary.