Predictive Cache Management Circuit for Efficiency

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Solution Overview

Problem

Current cache memory systems face inefficiencies due to suboptimal cache line eviction and insertion policies, leading to unnecessary data retrieval from main memory and reduced processor performance, particularly when data is evicted and later needed again or when cache pollution occurs.

Innovation Solution

A predictive cache management circuit that adjusts cache control policies based on persistent, history-based cache control information, using retention ranks to determine which data is least likely to be used, thereby optimizing cache line evictions and insertions to improve cache efficiency and processor performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If traditional cache control policies are used for cache line eviction and insertion, then the cache memory can operate with simple control logic, but cache efficiency deteriorates due to unnecessary data retrieval and cache pollution

Engineering Contradiction:
Improvecache efficiencyVSAvoidcache control policy complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The system performs preliminary actions by storing cache control information persistently before eviction occurs. The predictive adjustment circuit generates cache control information based on hit-miss indicators and retention ranks, then stores it persistently. This allows the system to make informed eviction decisions in the future without needing complex real-time analysis, thereby improving cache efficiency while managing complexity through proactive information gathering.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system implements feedback mechanisms by using hit-miss indicators from cache memory operations to generate and update cache control information. The predictive adjustment circuit receives feedback about cache performance (hits and misses) and adjusts retention ranks and eviction decisions accordingly. This feedback loop enables the system to learn from past performance and make better future decisions, improving overall cache efficiency.

Inventive Principle:
Principle #23Feedback

2Reliability

If data is evicted from cache memory based on current retention ranks, then cache lines can be managed with simple replacement policies, but processor performance deteriorates when evicted data is needed again soon

Engineering Contradiction:
Improvedata availability in cacheVSAvoidtime for data re-fetching
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system performs preliminary action by storing cache control information persistently before data eviction occurs. The predictive adjustment circuit generates cache control information based on hit-miss indicators and retention ranks, then stores it persistently in memory. This allows the system to make informed eviction decisions in the future without needing complex real-time analysis, thereby improving cache efficiency while managing complexity through proactive information gathering.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system implements feedback mechanisms by using hit-miss indicators from cache memory operations to generate and update cache control information. The predictive adjustment circuit receives feedback about cache performance (hits and misses) and adjusts retention ranks and eviction decisions accordingly. This feedback loop enables the system to learn from past performance and make better future decisions, improving overall cache efficiency.

Inventive Principle:
Principle #23Feedback

3Productivity

If cache lines are inserted and promoted based on standard policies, then cache memory operations can be performed with straightforward control logic, but cache pollution increases when data is loaded that will only be used once

Engineering Contradiction:
Improveprocessor performanceVSAvoidamount of cache pollution
Core Design Contradiction:
ProductivityVSQuantity of substance

Solution Approach 1:

The system performs preliminary actions by storing cache control information persistently before insertion occurs. The predictive adjustment circuit generates cache control information based on hit-miss indicators and retention ranks, then stores it persistently. This allows the system to make informed insertion decisions in the future without needing complex real-time analysis, thereby improving cache efficiency while managing complexity through proactive information gathering.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system changes parameters by using persistent cache control information to adjust retention ranks and insertion policies. The predictive adjustment circuit modifies retention rank assignments and cache line promotion decisions based on historical cache control information. This parameter adjustment enables the system to distinguish between frequently accessed data and data that will be used only once, reducing cache pollution while maintaining high processor performance.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP4165511B1Cache management circuits for predictive adjustment of cache control policies based on persistent, history-based cache control information
Publication Date: 2024.11.27 MICROSOFT TECHNOLOGY LICENSING LLC
  • EP4165511B1 patent drawingFigure 1
  • EP4165511B1 patent drawingFigure 2
  • EP4165511B1 patent drawingFigure 3

AI summary

A cache management circuit that includes a predictive adjustment circuit configured to predictively generate cache control information based on a cache hit-miss indicator and the retention ranks of accessed cache lines to improve cache efficiency is disclosed. The predictive adjustment circuit stores the cache control information persistently, independent of whether the data remains in cache memory. The stored cache control information is indicative of prior cache access activity for data from a memory address, which is indicative of the data's "usefulness." Based on the cache control information, the predictive adjustment circuit controls generation of retention ranks for data in the cache lines when the data is inserted, accessed, and evicted. After the data has been evicted from the cache memory and is later accessed by a subsequent memory request, the persistently stored cache control information corresponding to that memory address increases the information available for determining the usefulness of data.