Cache Memory System Using Temporal Locality Information
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Solution Overview
Problem
Existing cache memory systems face challenges in optimizing cache size to extend data lifetime and improve cache hit ratio without increasing data access time, particularly in direct mapping caches where data eviction can lead to cache misses due to limited victim cache size.
Innovation Solution
A cache memory system comprising a main cache, an extended cache, and a separation cache, where data evicted from the main cache is stored in the extended cache, and further transferred to a separation cache if temporal locality information meets a predetermined condition, allowing for efficient data management and eviction to lower-level memory when conditions are not met.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the size of a cache memory increases, then a lifetime of data and a cache hit ratio may increase, but a data access time may also increase
Solution Approach 1:
The cache memory is segmented into multiple levels (main cache, extended cache, victim cache, and separation cache). Data is divided into temporal and non-temporal categories, with temporal data stored in the separation cache to extend lifetime while maintaining fast access paths for both temporal and non-temporal data through the hierarchical structure.
2Loss of time
If a direct mapping cache is used, then a data access time when a cache hit occurs is short, but a cache hit ratio is relatively low
Solution Approach 1:
The extended cache and victim cache act as intermediary structures between the main cache and lower-level memory. When data is evicted from the main cache, it is first stored in the extended cache, and potentially in the victim cache or separation cache, providing additional opportunities for cache hits before data must be retrieved from slower memory.
3Reliability
If a victim cache is used to store previous data, then a cache hit ratio may improve, but data to be recycled may be evicted due to a small size of the victim cache
Solution Approach 1:
The cache hierarchy adds another dimension to data storage by introducing the separation cache that specifically handles temporal data. This creates an additional storage dimension beyond the traditional main cache-victim cache structure, allowing temporal data to be preserved longer without competing for limited victim cache space.
4Productivity
If data is repeatedly accessed over a short time, then data to be recycled may be evicted from a victim cache, but a cache miss may occur
Solution Approach 1:
The system performs preliminary classification of data into temporal and non-temporal categories using temporal locality information. Temporal data is proactively routed to the separation cache before it would be evicted from the main cache, ensuring that frequently accessed data remains in the cache hierarchy and preventing cache misses for repeatedly accessed data.
Data Source
AI summary
A cache memory system using temporal locality information and a data storage method are provided. The cache memory system including: a main cache which stores data accessed by a central processing unit; an extended cache which stores the data if the data is evicted from the main cache; and a separation cache which stores the data of the extended cache when the data of the extended cache is evicted from the extended cache and temporal locality information corresponding to the data of the extended cache satisfies a predetermined condition.