Coherency Manager Selective Data Retrieval Based on Access Latency
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Solution Overview
Problem
Conventional memory management schemes in processing systems are inefficient as they require data to be moved between caches and processing units, leading to increased memory access latency and reduced overall processing efficiency.
Innovation Solution
A processor system that selectively transfers data from either a cache or system memory based on dynamically estimated access latencies, using a coherency manager to identify and utilize the memory unit with the lowest access latency, thereby reducing memory access latency and improving processor performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data is moved between caches and processing units using conventional memory management schemes, then data can be accessed by processing units, but memory access latency increases and processing efficiency decreases
Solution Approach 1:
The system dynamically monitors access latency metrics for both cache and system memory, and adaptively selects the data source based on current latency conditions. This dynamic adaptation allows the system to respond to changing workload patterns and memory conditions, selecting the fastest available data source in real-time rather than following a fixed memory management hierarchy.
Solution Approach 2:
The invention changes the operational parameter of data source selection from a static hierarchy-based approach to a dynamic latency-based approach. By monitoring access latency metrics and using them to determine data retrieval location, the system optimizes memory access performance based on actual system conditions rather than predetermined memory management rules.
2Reliability
If data is moved between caches and processing units using conventional memory management schemes, then data can be accessed by processing units, but overall processing efficiency is reduced
Solution Approach 1:
The system dynamically adjusts data retrieval strategy based on real-time latency measurements, enabling processing units to access data from the most performant source available. This dynamic optimization directly improves processing efficiency by minimizing wait times for data access while maintaining reliable data availability across the memory hierarchy.
Solution Approach 2:
The system implements feedback mechanisms by monitoring access latency metrics from the memory hierarchy and using this information to make intelligent decisions about data retrieval locations. This feedback loop enables continuous optimization of data access patterns, improving overall processing efficiency by learning from and adapting to actual system performance characteristics.
Data Source
AI summary
A processor includes multiple processing units (e.g., processor cores), with each processing unit associated with at least one private, dedicated cache. The processor is also associated with a system memory that stores all data that can be accessed by the multiple processing units. A coherency manager (e.g., a coherence directory) of the processor enforces a specified coherency scheme to ensure data coherency between the different caches and between the caches and the system memory. In response to a memory access request to a given cache resulting in a cache miss, the coherency manager identifies the current access latency to the system memory as well as the current access latencies to other caches of the processor. The coherency manager transfers the targeted data to the given cache from the cache or system memory having the lower access latency.