Processor Register Architecture for Zero-Cycle Context Switching
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Solution Overview
Problem
Conventional context switches in computing are computationally intensive and power-consuming, often requiring multiple clock cycles and additional memory access, which are inadequate for timing-critical applications like low latency 5G new radio services.
Innovation Solution
A zero-cycle context switch is implemented using a processor with dedicated registers for regular and interrupt service threads, allowing the switch to occur within a single clock cycle without copying data to external memory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional context switch is implemented across multiple clock cycles with memory access, then thread state can be saved and restored, but processing time increases and power consumption increases
Solution Approach 1:
The processor is segmented into multiple register files, with each register file dedicated to storing state information for specific threads. This segmentation allows the processor to maintain thread states in separate, dedicated storage units, enabling rapid context switching without needing to access external memory, thus reducing context switch duration while preserving thread state reliability
Solution Approach 2:
Thread state information is preliminarily stored in the dedicated register files before context switching is needed. The register files are pre-configured to hold the necessary thread state, so when a context switch is required, the processor can immediately switch between pre-prepared thread states without performing time-consuming memory access operations
2Reliability
If a conventional context switch uses external memory access, then thread state can be stored, but silicon footprint increases and manufacturing cost increases
Solution Approach 1:
The processor merges the thread state storage function directly into the register files that are already part of the processor core. By combining the state storage capability with the existing register infrastructure, the design eliminates the need for separate external memory components, thereby reducing silicon footprint while maintaining reliable thread state storage
Solution Approach 2:
The dedicated register files serve multiple functions: they act as both general-purpose registers for thread operations and as dedicated storage for thread state information during context switching. This multi-functionality eliminates the need for separate specialized storage components, reducing overall silicon footprint while ensuring reliable thread state preservation
3Reliability
If a conventional context switch performs multiple operations including memory access, then thread state can be saved and restored, but power consumption increases
Solution Approach 1:
The design extracts the time-consuming and power-intensive memory access operation from the context switch process. By taking out the memory access step and replacing it with direct register file operations, the processor achieves reliable thread state management through faster, lower-power register-based operations
Solution Approach 2:
The patent substitutes the mechanical/memory-based state storage system with a register-based system. By replacing external memory access with internal register file operations, the design eliminates the high-power memory access operations while maintaining the essential function of thread state saving and restoration
Data Source
AI summary
According to one aspect of the present disclosure, a processor is disclosed. The processor may include a plurality of registers. The plurality of registers may include a first set of registers associated with a regular mode thread. The plurality of registers may also include a second set of registers associated with an interrupt service thread. The processor may also include a processing core. The processing core may be configured to perform first operations associated with the regular mode thread. The processing core may be configured to receive an interrupt service signal associated with the interrupt service thread. In response to the interrupt service signal, the processing core may be configured to implement a zero-cycle context switch to perform second operations associated with the interrupt service thread using the second set of registers.