Flash Memory Controller L2P Address Caching via SRAM Node Index
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Solution Overview
Problem
The frequent checking of the group-to-flash (G2F) mapping table in flash memory controllers negatively affects response times and read/write performance due to the limited capacity of dynamic random access memory (DRAM) and the large size of the logical-to-physical (L2P) mapping table.
Innovation Solution
Caching node indexes from the G2F mapping table in static random access memory (SRAM) and storing L2P addresses of host write commands in a cached L2P address array within the SRAM, allowing for direct access and reducing the need for repeated G2F mapping table checks during host read/write operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the G2F mapping table is frequently checked to determine L2P mapping table locations, then the system can handle host read/write commands with limited DRAM capacity, but the response time deteriorates and read/write performance decreases
Solution Approach 1:
The patent applies preliminary action by pre-loading the G2F mapping table into the DRAM before handling host read/write commands. This allows the controller to have immediate access to the mapping information without repeatedly checking the flash memory during command processing, thus reducing response time while maintaining the ability to handle commands with limited DRAM capacity
Solution Approach 2:
The patent introduces an intermediary mechanism by using a cache memory structure that stores recently accessed G2F mapping table entries. This intermediary cache acts as a buffer between the flash memory and the processing logic, reducing the frequency of direct G2F table checks and improving overall system response time
2Adaptability or versatility
If the G2F mapping table is checked repeatedly to update L2P addresses during host write commands, then data can be moved to different physical locations, but the time required for updating L2P addresses increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing the mapping between logical addresses and physical locations in the G2F mapping table before write operations. When host write commands arrive, the controller can directly retrieve the target physical location information from the pre-loaded G2F table in DRAM, eliminating the need for repeated checks during data movement and address updates
Solution Approach 2:
The patent uses copying by creating and maintaining a cached copy of the G2F mapping table in the DRAM memory. This cached copy contains the essential mapping information needed for address translation during write operations, allowing the system to update L2P addresses by referencing the cached copy rather than repeatedly accessing the original flash memory-based G2F table
Data Source
AI summary
A method of caching mapping table for use in a flash memory device having a flash memory controller and a flash memory is provided. The method includes: in response to a host read/write command, checking a G2F mapping table to determine whether a required group of a L2P mapping table has been loaded to a DRAM of the flash memory controller and accordingly obtain a node index indicating which memory node of the DRAM the group is stored in; recording the node index to a first region of a SRAM of the flash memory controller; accessing the DRAM to obtain an L2P address indicating a physical address that is associated with the host read/write command from the group of the L2P mapping table by referencing the node index stored in the first region of the SRAM; and performing a read/write operation on the flash memory according to the L2P address.