Single Instruction Register Save Restore for Interrupt Latency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current data processing systems face high interrupt latency due to the time-consuming process of saving and restoring processor states during interrupt handling, which can lead to missed higher priority interrupts and reduced system reliability, especially in real-time embedded systems.
Innovation Solution
The introduction of single instructions that can store or load subsets of registers, including both general purpose registers (GPRs) and special purpose registers (SPRs), without the need for mask values, allowing for the saving and loading of non-contiguous register subsets, thereby reducing the number of instructions required and enabling interruptible operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple registers are saved and restored using traditional methods with multiple instructions, then the processor state can be fully preserved, but the interrupt latency increases and system reliability decreases
Solution Approach 1:
The patent combines multiple separate save and restore instructions into a single integrated instruction that can save or restore multiple registers (including GPRs and SPRs) in one operation. This merging eliminates the sequential execution overhead of multiple instructions, thereby reducing interrupt latency while maintaining complete processor state preservation.
Solution Approach 2:
The patent segments the register set into different categories (GPRs and SPRs) and provides specific single instructions for saving/restoring each category. This segmentation allows the processor to use optimized pathways for different register types, reducing the overall time required for state preservation compared to treating all registers uniformly with multiple generic instructions.
2Productivity
If the time to save and restore processor state is reduced, then interrupt latency decreases and higher priority interrupts can be handled, but the complexity of the loading/storing mechanism increases
Solution Approach 1:
The patent creates universal save and restore instructions that can handle multiple types of registers (both GPRs and SPRs) within a single instruction. This multi-functionality reduces the total number of instructions needed while managing complexity through standardized instruction formats that the processor can decode and execute efficiently.
Solution Approach 2:
The single save/restore instructions automatically manage the entire processor state preservation process without requiring multiple separate operations. The instruction itself performs the complete save or restore operation, eliminating the need for complex sequences of multiple instructions and reducing both time and complexity.
3Quantity of substance
If traditional multiple instructions are used for saving registers, then all register states can be saved, but the number of instructions required increases to 20 or more
Solution Approach 1:
The patent merges the functionality of 20 or more separate save instructions into a single integrated instruction that can preserve the state of multiple registers simultaneously. This dramatic reduction in instruction count directly translates to reduced execution time and fewer pipeline stages that need to be completed during interrupt handling.
Data Source
AI summary
A method for operating a data processing system includes providing an application binary interface (ABI) which determines a set of non-contiguous volatile registers and a set of non-volatile registers. The set of non-contiguous volatile registers includes a plurality of general purpose registers (GPRs) and a plurality of special purpose registers (SPRs). The method includes providing less than three instructions which collectively load or store all of the set of non-contiguous volatile registers determined by the ABI. A system includes a set of volatile registers including a plurality of volatile GPRs, a plurality of volatile supervisor SPRs, and a plurality of volatile user SPRs, and execution circuitry for executing a first instruction that loads or stores the plurality of volatile supervisor SPRs, for executing a second instruction that loads or stores the plurality of volatile GPRs, and for executing a third instruction that loads or stores the plurality of volatile user SPRs.