Dynamic Memory Passive Data Expiration Architecture
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Solution Overview
Problem
Conventional dynamic memory architectures for cache memory systems require periodic refresh operations, leading to increased overhead and resource burden, as they typically refresh all data regardless of usage, which is unnecessary in a cache environment where data can be considered 'dead' if not referenced for a long time.
Innovation Solution
A passive expiration methodology that uses error encoding and decoding circuits, such as Berger codes, or time stamps to detect and manage expired data in dynamic memory, allowing data to expire without periodic refresh, thus reducing administrative and processing overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If periodic refresh operations are performed on all dynamic memory data, then data reliability is maintained, but system overhead and resource consumption increase
Solution Approach 1:
The patent applies partial action by performing refresh operations only on a subset of memory cells that are likely to be accessed again, rather than refreshing all memory cells. The system identifies recently accessed memory addresses and selectively refreshes only those cells, reducing refresh overhead while maintaining data reliability for actively used data.
Solution Approach 2:
The patent uses preliminary action by pre-loading frequently accessed data into a small, fast buffer memory before it would otherwise be needed. This allows the system to anticipate and prepare for future access patterns, reducing the need for frequent refresh operations on predictable data while maintaining availability.
2Quantity of substance
If dynamic memory is used for cache, then storage density increases, but data loss occurs due to leakage without periodic refresh
Solution Approach 1:
The patent selectively applies refresh operations only to memory cells containing data that is likely to be accessed again, rather than refreshing all cells. This partial action maintains data integrity for relevant data while allowing other data to decay, thus preserving storage capacity without comprehensive refresh overhead.
Solution Approach 2:
The patent treats cache data as disposable by allowing data to decay without refresh when it is not accessed. The system accepts that some data will be lost but relies on the fact that frequently accessed data will be refreshed, making the system effective for its primary purpose of caching hot data rather than persistent storage.
3Productivity
If restore tracking system is implemented to reduce refresh actions, then refresh overhead decreases, but system complexity and overhead increase
Solution Approach 1:
The patent makes the existing cache tag structure multi-functional by using it to track both data validity and access patterns for refresh decisions. Instead of adding separate tracking hardware, the system repurposes existing cache metadata to serve dual purposes: traditional cache tagging and refresh management, thereby reducing overall system complexity.
Solution Approach 2:
The patent merges the refresh management function with the existing cache control logic. By combining these functions into a unified control mechanism that uses the same metadata and control signals for both cache operation and refresh scheduling, the system reduces overhead while maintaining productivity.
Data Source
AI summary
Apparatus for passively tracking expired data in a dynamic memory includes a time stamp memory configurable for storing information relating to a refresh status of one or more corresponding data entries in the dynamic memory. The apparatus further includes a timer configurable for defining a desired window of time in which a refresh operation of data in the dynamic memory is to occur in order to ensure that the data is valid. Control circuitry is coupled to the time stamp memory and to the timer. The control circuitry is operative to manage the information stored in the time stamp memory relating to the refresh status of the one or more corresponding data entries in the dynamic memory.