Microarchitectural Scratchpad State Restore for Fast Context Switching

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Solution Overview

Problem

Modern processors face challenges in maintaining pattern recognition abilities of microarchitectural registers due to frequent context switches, as they may not be sufficiently warmed up before switching to a new program, leading to repeated pattern recognition and increased latency.

Innovation Solution

Implementing a microarchitectural scratchpad to store program state data, including the state of microarchitectural registers, allowing processors to restore the program state immediately upon context switch, thereby reducing the need for a warm-up period.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If frequent context switches are performed to handle multiple programs, then program execution flexibility is improved, but microarchitectural register warm-up time is lost repeatedly

Engineering Contradiction:
Improveprogram execution flexibilityVSAvoidmicroarchitectural register warm-up time
Core Design Contradiction:
Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent stores the state of microarchitectural registers in a buffer during program execution. When a context switch occurs, the previously executed program's register state is retrieved from the buffer and restored, effectively performing the warm-up action in advance and eliminating the need for repeated warm-up periods.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent creates a copy of the microarchitectural register state and stores it in a buffer. This copy can be quickly restored when needed, allowing the processor to resume program execution without repeating the pattern recognition process that occurred during the original warm-up period.

Inventive Principle:
Principle #26Copying

2Ease of operation

If microarchitectural register state is not restored during context switch, then context switching simplicity is maintained, but pattern recognition ability deteriorates

Engineering Contradiction:
Improvecontext switching simplicityVSAvoidpattern recognition ability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The buffer stores the microarchitectural register state in advance during program execution. When context switching occurs, this pre-stored state is retrieved and restored, ensuring pattern recognition ability is maintained without adding complexity to the context switching mechanism itself.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If buffer size is increased to store more program state data, then program state restoration completeness is improved, but memory resource consumption increases

Engineering Contradiction:
Improveprogram state restoration completenessVSAvoidmemory resource consumption
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent selectively stores the state of microarchitectural registers in the buffer, focusing on the specific components needed for pattern recognition rather than storing the entire processor state. This targeted approach ensures restoration completeness for critical components while minimizing memory resource consumption.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP4660800A1Restoring program states using microarchitectural scratchpads
Publication Date: 2025.12.10 GOOGLE LLC
  • EP4660800A1 patent drawingFigure 1
  • EP4660800A1 patent drawingFigure 2
  • EP4660800A1 patent drawingFigure 3

AI summary

Aspects of the disclosed technology include techniques and mechanisms for restoring program states using microarchitectural scratchpads. A processor is configured to store, in a buffer, program state data which indicates a current state of microarchitectural registers therein during execution of a current program. Based on receiving a command to terminate execution of the current program and restore execution of a different program, the processor retrieves, from the buffer, the program state data associated with the program to be executed and restores the retrieved data.