Cache Coherence Ping-Pong Detection and Mode Switching
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Solution Overview
Problem
In multi-processor systems, data inconsistency and unnecessary transactions due to cache coherence issues lead to reduced performance and increased waiting times and bus traffic, particularly exacerbated by the ping-pong phenomenon in migratory sharing methods.
Innovation Solution
A cache consistency management device and method that monitors ping-pong migration sequences between processors, counts successive generations, and modifies the coherence management mode to switch from migratory to non-migratory sharing methods based on threshold counts, thereby reducing unnecessary transactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a migratory sharing method is used for cache coherence management, then data consistency between processors is improved, but processor waiting time and bus traffic increase due to ping-pong migration sequences
Solution Approach 1:
The system dynamically switches between migratory and non-migratory sharing methods based on the detected ping-pong migration sequence count. When ping-pong sequences exceed a threshold, the system transitions from migratory to non-migratory sharing, adapting the coherence management strategy to current system conditions to reduce waiting time while maintaining data consistency.
Solution Approach 2:
The invention changes the coherence management parameter (sharing method type) based on the counted ping-pong migration sequences. By monitoring the sequence count and comparing it against thresholds, the system modifies the sharing method parameter to optimize performance, reducing processor waiting time when ping-pong sequences are detected.
2Reliability
If a migratory sharing method is used for cache coherence management, then data consistency between processors is improved, but bus traffic increases due to unnecessary migration requests
Solution Approach 1:
The system dynamically adjusts the sharing method based on real-time detection of ping-pong migration sequences. When excessive sequences are detected, the system switches to non-migratory sharing, which eliminates unnecessary migration requests and reduces bus traffic while preserving data consistency through alternative coherence management mechanisms.
Solution Approach 2:
The invention modifies the coherence management parameter (sharing method) based on the counted ping-pong sequences. By changing from migratory to non-migratory sharing when thresholds are exceeded, the system reduces bus traffic and energy consumption associated with unnecessary migration requests while maintaining data consistency.
3Productivity
If ping-pong migration sequences are monitored and counted, then unnecessary transactions can be reduced, but device complexity increases
Solution Approach 1:
The coherence management device is segmented into distinct functional units: a monitoring unit that detects ping-pong migration sequences, a counting unit that tracks sequence occurrences, and a sharing method determination unit that decides whether to switch methods. This segmentation allows the system to add monitoring functionality while maintaining clear separation of concerns and modular architecture.
Solution Approach 2:
The invention introduces an intermediary coherence management device that sits between processors and the cache coherence protocol. This intermediary monitors migration sequences, counts them, and determines sharing methods, acting as a mediator that reduces unnecessary transactions without requiring fundamental changes to the underlying processor architecture or cache protocol.
Data Source
AI summary
A cache consistency management device according to example embodiments comprises a ping-pong monitoring unit monitoring a ping-pong migration sequence generated between a plurality of processors; a counting unit counting the number of successive generations of the ping-pong migration sequence in response to the monitoring result; and a request modifying unit modifying a migration request to a request of a non-migratory sharing method on the basis of the counting result.