Relinquish Instruction for Unused Storage Circuit Management
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Solution Overview
Problem
Data processing apparatuses face inefficiencies due to the presence of unused storage circuits, which can cause stalls during speculative execution and increase context switching time, as they need to be saved and restored during process changes.
Innovation Solution
Incorporating a relinquish instruction that indicates unused storage circuits, allowing the execution circuitry to modify the execution of future instructions based on the state of these circuits, thereby reducing unnecessary operations and saving only used storage circuits during context switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all storage circuits are saved during context switching, then data integrity is maintained, but context switching time increases
Solution Approach 1:
The patent extracts only the necessary storage circuits (those that are live or marked as used) from the full set of storage circuits during context switching. The relinquish instruction mechanism allows the system to identify and exclude unused storage circuits from the save operation, thereby reducing context switching time while maintaining data integrity for only those circuits that actually need to be preserved.
2Speed
If speculative execution is performed without checking storage circuit usage, then execution speed increases, but stalls occur when branches are incorrectly predicted
Solution Approach 1:
The patent applies preliminary action by having the relinquish instruction mark storage circuits as unused before speculative execution occurs. This pre-marking allows the execution unit to safely overwrite storage circuits during speculative execution without causing stalls, because the system has already determined that these circuits are not needed by other instructions. If speculation is incorrect, the harm is limited to already-marked-unused circuits.
3Reliability
If storage circuits are frequently saved and restored, then context switching reliability is maintained, but processing efficiency decreases
Solution Approach 1:
The patent implements partial action by saving only a subset of storage circuits—specifically, those that are live or have been marked as used via the relinquish instruction mechanism. This partial save approach maintains context switching reliability for the necessary circuits while avoiding the overhead of saving and restoring all storage circuits, thereby improving processing efficiency.
Data Source
AI summary
A data processing apparatus is provided comprising: a plurality of storage circuits to store data. Execution circuitry performs one or more operations using the storage circuits in response to instructions. The instructions include a relinquish instruction. The execution circuitry responds to the relinquish instruction by indicating that at least one of the plurality of storage circuits is an unused storage circuit and the execution circuitry affects execution of future instructions based on the unused storage circuit after executing the relinquish instruction.