Processor Context Switching via Selective Register File Segmentation
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Solution Overview
Problem
The existing processor technologies face inefficiencies in context switching due to the overhead of storing and restoring data in registers during interrupt service routines, leading to increased processing time and potential thrashing.
Innovation Solution
The implementation of a processor with a write buffer and shadow registers to manage data transfer, allowing for selective storage and restoration of data in memory based on set values, reducing the need for full register backup during interrupt service routines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the processor stores all data stored in all registers in the memory during interrupt service routine, then the context switching is complete, but the context switching overhead increases and processing time increases
Solution Approach 1:
The patent segments the register file into a first register file and a second register file, with the second register file being copied to the first register file only when necessary. This segmentation allows selective context saving rather than saving all register data, reducing the overhead while maintaining reliability.
Solution Approach 2:
The patent extracts only the necessary register data (from the second register file) to be saved in memory during interrupt service routine, rather than saving all register data. This extraction approach reduces the amount of data transferred while maintaining the essential context information.
2Reliability
If the processor stores all data stored in all registers in the memory during interrupt service routine, then the context switching is complete, but the context switching overhead increases
Solution Approach 1:
The patent segments the register file into a first register file and a second register file, with the second register file being copied to the first register file only when necessary. This segmentation allows selective context saving rather than saving all register data, reducing the overhead while maintaining reliability.
Solution Approach 2:
The patent extracts only the necessary register data (from the second register file) to be saved in memory during interrupt service routine, rather than saving all register data. This extraction approach reduces the amount of data transferred while maintaining the essential context information.
3Productivity
If the processor uses shadow registers to store data, then data transfer is optimized, but the device complexity increases
Solution Approach 1:
The patent creates a copy of the register file (second register file) that can be selectively copied to the first register file. This copying mechanism optimizes data transfer by allowing partial updates rather than full copies, improving productivity while managing complexity through structured duplication.
Data Source
AI summary
A processor includes a register file, a context controller that, in response to a target interrupt occurring, is configured to determine, a target register that stores new data acquired through each of commands for executing an interrupt service routine (ISR) among the plurality of registers, a write buffer configured to transmit pre-data stored in the target register to a memory, and a flag register configured to store set data including set values indicating whether the new data is stored in each of the registers. The context controller is configured to determine whether to transfer the pre-data to the memory through the write buffer based on the set data.