Logical to Physical Table Compression in Memory Systems
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Solution Overview
Problem
Memory systems face performance degradation due to the size limitations of the cache for logical-to-physical (L2P) tables, leading to increased latency and reduced efficiency in read, write, and erase operations, as frequently loading portions of the L2P table from non-volatile storage to cache consumes resources and decreases available space for user data.
Innovation Solution
The solution involves rearranging logical address regions to correspond to continuous physical addresses, allowing the L2P table to store only the first address and an indicator, reducing the cache size requirements and increasing the number of regions stored, thereby minimizing the need for frequent data loading from non-volatile storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the L2P table is stored entirely in cache, then access speed is improved, but cache size requirements increase, reducing available space for user data
Solution Approach 1:
The L2P table is divided into multiple regions, each mapped to a specific logical address region. Only the necessary portions of the L2P table are loaded into cache based on current access patterns, rather than loading the entire table. This segmentation allows the system to maintain fast access speeds for active regions while significantly reducing the cache size requirement.
Solution Approach 2:
The system pre-loads only the portions of the L2P table that are likely to be accessed soon based on predicted access patterns. By anticipating which logical address regions will be accessed next, the system prepares the corresponding L2P table regions in advance, maintaining fast access speeds without needing to cache the entire table.
2Loss of time
If portions of the L2P table are frequently loaded from non-volatile storage to cache, then access latency is reduced, but system overhead increases and power consumption rises
Solution Approach 1:
The system implements different caching strategies for different regions of the L2P table based on their access characteristics. Frequently accessed regions are kept in cache with higher priority, while less frequently accessed regions remain in non-volatile storage. This localized quality approach reduces overall power consumption by minimizing data transfers while maintaining low latency for critical regions.
Solution Approach 2:
The system periodically updates and refreshes the L2P table regions in cache based on changing access patterns. Instead of continuously loading all regions, the system uses periodic refresh cycles to update only the necessary portions, reducing power consumption associated with frequent data transfers while maintaining acceptable access latency through timely updates.
3Quantity of substance
If the L2P table is compressed to reduce cache size, then more regions can be stored in cache, but access complexity increases
Solution Approach 1:
The system introduces an intermediary layer (translation buffer or mapping structure) between the compressed L2P table and the cache. This intermediary maintains the compressed representation while providing efficient access paths to the actual data locations. The intermediary handles the complexity of decompression and address translation, allowing the cache to store more regions without significantly increasing access complexity for the main system.
Data Source
AI summary
Methods, systems, and devices for data organization for logical to physical table compression are described. The memory system may identify a region that includes one or more logical addresses associated with discontinuous corresponding physical addresses. The memory system may include a plurality of regions of logical addresses and a plurality of memory cells arranged according to a plurality of physical addresses. The memory system may determine a period of inactivity of access operations on the plurality of memory cells and rearrange, during the period of inactivity, information stored within the discontinuous corresponding physical addresses to be within continuous physical addresses of the plurality of physical addresses.