Flash Memory Controller Wear-Leveling via Hot Page Distribution
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Solution Overview
Problem
Conventional wear-leveling techniques for flash memory devices are inefficient as they perform unnecessary read and write operations, causing performance deterioration and reducing the lifespan of the device, due to their reliance on predetermined time or operation counts, and inability to implement algorithms requiring partial programming.
Innovation Solution
A memory controller with a hot page decision unit and address translation unit that classifies pages into hot and cold pages, rearranging hot pages across different blocks to distribute wear evenly, minimizing unnecessary operations during the merge process and optimizing wear-leveling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional wear-leveling algorithms are used, then wear-leveling is achieved, but unnecessary read and write operations are performed causing performance deterioration
Solution Approach 1:
The patent implements dynamic wear-leveling by continuously monitoring the actual wear state of each block through counters that track the number of erase operations. Instead of using static predetermined time or operation counts, the system adapts its wear-leveling decisions based on real-time wear data, allowing it to perform wear-leveling only when and where actually needed, thus avoiding unnecessary operations while maintaining reliability
Solution Approach 2:
The patent employs feedback mechanisms where the memory controller reads wear counters from flash memory blocks to determine their actual wear state. This feedback information is used to make informed decisions about which blocks should be candidates for wear-leveling operations, replacing the conventional blind approach of performing wear-leveling based on predetermined schedules with an intelligent feedback-driven system that minimizes unnecessary operations
2Device complexity
If wear-leveling is performed based on predetermined time or operation counts, then wear-leveling is simplified to implement, but it causes unnecessary operations and reduces device lifespan
Solution Approach 1:
The patent uses feedback from wear counters to dynamically adjust wear-leveling operations. By continuously monitoring actual block wear through read operations on counter data, the system can determine when wear-leveling is actually necessary, preventing premature or unnecessary operations that would waste device erase cycles and reduce overall lifespan
Solution Approach 2:
The patent changes the parameter basis for wear-leveling from static predetermined time or operation counts to dynamic wear state parameters measured by counters. This parameter change allows the system to adapt wear-leveling timing and frequency to actual device conditions, extending device lifespan by avoiding unnecessary erase operations while maintaining manageable implementation complexity
3Productivity
If algorithms requiring partial programming are implemented, then wear-leveling efficiency is improved, but hardware constraints are exceeded
Solution Approach 1:
The patent segments the wear-leveling process into manageable components: identifying candidate blocks based on wear counters, selecting target blocks for programming, and executing partial programming operations. This segmentation allows complex wear-leveling algorithms to be implemented through coordinated software control rather than requiring complex hardware changes, improving wear-leveling efficiency while respecting hardware constraints
Solution Approach 2:
The patent introduces wear counters as intermediary elements that mediate between the host system and flash memory blocks. These counters provide the necessary information about block wear states, enabling sophisticated wear-leveling algorithms to operate efficiently by using the counters as intermediaries for decision-making, thereby improving productivity without exceeding hardware constraints
Data Source
AI summary
The present invention provides a flash memory controller for mapping the logical addresses to the physical addresses of memory including a plurality of blocks, each having a plurality of pages, wherein the memory controller includes a processor. The processor includes hot page decision unit and an address translation unit. The hot page decision unit classifies pages in each block into hot pages and cold pages based on a predetermined criterion. When there is a plurality of the classified hot pages, the address translation unit respectively arranges the classified hot pages in different target blocks.In accordance with this configuration, upon performing a merge operation, hot pages and cold pages are determined, and the hot pages are respectively distributed to empty blocks, so that concentration of an erase operation on a specific physical block may be avoided, thus wear-leveling may be performed more efficiently.