Cache Invalidation Range Tracking for Invalidate-Write Hazards

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Solution Overview

Problem

Existing data processing systems face challenges in managing invalidate-write hazards during cache invalidation, leading to potential data loss and inefficiencies in memory system bandwidth and power consumption due to unnecessary writebacks of dirty data.

Innovation Solution

Implementing hardware-based invalidation range tracking circuitry to track cache invalidation target addresses, cache invalidation circuitry to request invalidation of corresponding entries, and invalidate-write hazard detection circuitry to prevent memory write requests until cache invalidation is complete, thereby reducing software overhead and ensuring data integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If cache invalidation is performed for large address ranges, then cache capacity is freed for new data allocation, but unnecessary writebacks of dirty data occur consuming memory bandwidth and power

Engineering Contradiction:

Improvecache allocation efficiencyVSAvoidpower consumption

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The patent applies preliminary action by performing address range tracking and invalidate-write hazard detection before cache invalidation is executed. The system pre-identifies address ranges that are targets for invalidation and monitors write requests to these ranges in advance, preventing unnecessary writebacks of dirty data before they occur, thereby saving power and memory bandwidth.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If software-based solutions are used to manage invalidate-write hazards, then hazard detection is possible, but system complexity increases and performance deteriorates due to cumbersome software overhead

Engineering Contradiction:

Improvehazard detection capabilityVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the software-based hazard detection mechanism with a hardware-based solution. The invalidation range tracking circuitry and hazard detection logic are implemented in hardware, substituting the mechanical/software approach with an electronic/hardware approach, thereby reducing software overhead and system complexity while maintaining reliable hazard detection.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If dirty data is written back to memory during cache invalidation, then cache entries are cleared for new allocation, but memory system bandwidth is consumed unnecessarily

Engineering Contradiction:

Improvecache turnover rateVSAvoidmemory bandwidth

Core Design Contradiction:

ProductivityVSQuantity of substance

Solution Approach 1:

The patent converts the potential harm of unnecessary writebacks into a benefit by implementing hazard detection that identifies when writebacks would be redundant. By detecting invalidate-write hazards, the system prevents writebacks of data that is about to be invalidated anyway, thereby conserving memory bandwidth while maintaining efficient cache turnover for valid data.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS12619535B2Invalidate-write hazard detection

Publication Date: 2026.05.05 ARM LTD

AI summary

An apparatus comprises invalidation range tracking circuitry to track at least one invalidation target address range specified as a target for cache invalidation; cache invalidation circuitry to request invalidation of cache entries corresponding to addresses in said at least one invalidation target address range tracked by the invalidation range tracking circuitry; and invalidate-write hazard detection circuitry to detect invalidate-write hazards based on a comparison of a write target address specified by a memory write request with the at least one invalidation target address range tracked by the invalidation range tracking circuitry.