Cache Memory Compression Across Hierarchy Levels for Low Latency
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Solution Overview
Problem
Existing cache memory systems face challenges in efficiently storing data due to limited capacity, as they often need to evict or discard existing data to make room for new data, and existing compression techniques either do not provide sufficient space reduction or introduce unacceptable latency, making it difficult to find a single compression method suitable for all levels of cache memories.
Innovation Solution
The use of a combination of lighter-weight and heavier-weight compression methods across different levels of cache memories, where lighter-weight compression is used for higher-level caches to minimize latency and heavier-weight compression is used for lower-level caches to achieve greater space reduction, allowing for efficient data storage without significant latency impacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If heavier-weight compression is used to compress data for storage in cache memories, then the data size reduction is improved, but the compression and decompression time increases
Solution Approach 1:
The patent segments the cache memory hierarchy into different levels (L1, L2, L3 caches) and applies different compression techniques to each level. Higher-level caches use lighter-weight compression to minimize latency impact, while lower-level caches use heavier-weight compression to achieve greater space reduction. This segmentation allows each cache level to operate with compression appropriate to its performance requirements.
Solution Approach 2:
The patent applies the principle of local quality by tailoring the compression characteristics to specific locations in the cache hierarchy. Each cache level receives a customized compression approach: faster, lighter compression for caches closer to the processor where speed is critical, and more aggressive compression for distant caches where capacity is the limiting factor.
2Speed
If lighter-weight compression is used to reduce compression latency, then the response time is improved, but the data size reduction is insufficient
Solution Approach 1:
The patent divides the cache memory system into multiple levels and assigns different compression strategies to each segment. Lighter-weight compression is applied to higher-level caches where speed is paramount, while heavier-weight compression is applied to lower-level caches where maximizing storage capacity is the priority. This segmentation ensures that no single cache level is bottlenecked by inappropriate compression choices.
Solution Approach 2:
The patent implements local quality by optimizing compression characteristics for each specific cache level's requirements. Higher-level caches receive faster compression optimized for minimal latency impact, while lower-level caches receive more aggressive compression optimized for maximum space utilization. Each location in the hierarchy gets the quality of compression appropriate to its function.
3Device complexity
If a single compression method is used for all cache memories, then the system complexity is reduced, but the performance optimization for different cache levels is insufficient
Solution Approach 1:
The patent segments the cache memory hierarchy into distinct levels and applies different compression techniques to each segment. This segmentation enables performance optimization for each cache level's specific requirements while maintaining a manageable level of overall system complexity through systematic organization.
Solution Approach 2:
The patent applies local quality by customizing compression characteristics for each cache level rather than using a uniform approach. This allows each cache level to be optimized for its specific performance and capacity requirements, improving overall system productivity without excessive complexity.
Data Source
AI summary
An electronic device includes at least one compression-decompression functional block and a hierarchy of cache memories with a first cache memory and a second cache memory. The at least one compression-decompression functional block receives data in an uncompressed state, compresses the data using one of a first compression or a second compression, and, after compressing the data, provides the data to the first cache memory for storage therein. When the data is retrieved from the first cache memory to be stored in the second cache memory, when the data is compressed using the first compression, the compression-decompression functional block decompresses the data to reverse effects of the first compression on the data, thereby restoring the data to the uncompressed state and provides the data compressed using the second compression or in the uncompressed state to the second cache memory for storage therein.