Memory Management for Flash Wear Leveling and Speed Stability
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Solution Overview
Problem
Flash memory performance is compromised due to the presence of bad physical erasing units in super physical units, leading to unstable speed and reduced bandwidth, as these units become idle and are not effectively utilized, resulting in wasted resources and reduced service life.
Innovation Solution
A memory management method that selects a set of super physical units based on the number rate of good and partial good super physical units, ensuring data is written into good physical erasing units, thereby averaging the probability of bad units and promoting wear leveling across the rewritable non-volatile memory module.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If partial good super physical units containing bad physical erasing units are continuously selected for writing data, then the service life of the memory module is extended by utilizing all available units, but the writing speed continuously drops and becomes unstable
Solution Approach 1:
The patent implements dynamic selection of super physical units based on real-time monitoring of bad unit distribution. The system adjusts which channels and super physical units are selected for writing operations, transitioning from static allocation to dynamic adaptation. This allows the system to maintain stable writing speed by avoiding concentration of bad units in selected channels while still utilizing partial good super physical units to extend service life.
Solution Approach 2:
The system changes the selection parameters for super physical units by introducing a threshold mechanism for bad unit concentration. Instead of uniformly selecting from all available units, the system modifies selection criteria to exclude super physical units that would cause bad unit concentration exceeding a predetermined threshold, thereby maintaining speed stability while extending service life.
2Stability of the object's composition
If bad physical erasing units are excluded from selection, then writing speed stability is improved, but the utilization rate of physical erasing units decreases and service life is reduced
Solution Approach 1:
The patent applies local quality by treating different channels and super physical units differently based on their bad unit composition. Instead of a uniform exclusion policy, the system selectively utilizes partial good super physical units where bad units are distributed below the threshold, while excluding only those where bad unit concentration would cause instability. This localized differentiation maintains speed stability while maximizing unit utilization.
Solution Approach 2:
The system performs partial utilization of super physical units by selecting only the good physical erasing units within partial good super physical units, while excluding the bad ones. This partial action approach allows the system to use available capacity without the excessive action of including bad units that would compromise speed stability, thereby achieving both goals.
3Productivity
If multi-channel design is adopted to increase bandwidth, then the maximum speed is improved, but the complexity of managing bad physical erasing units across channels increases
Solution Approach 1:
The patent segments the multi-channel system into independent evaluation units, where each channel and super physical unit is assessed separately for bad unit concentration. This segmentation allows the complex multi-channel management to be broken down into simpler, independent decisions for each unit, reducing overall management complexity while maintaining high bandwidth utilization through parallel operations.
Solution Approach 2:
The system performs preliminary classification of super physical units into good, partial good, and bad categories before writing operations. By pre-evaluating and categorizing units based on their bad unit composition, the system simplifies subsequent selection decisions during writing operations, reducing real-time management complexity while maintaining optimal bandwidth utilization.
Data Source
AI summary
A memory management method for a rewritable non-volatile memory module, a memory control circuit unit and a memory storage apparatus are provided. The rewritable non-volatile memory module includes a plurality of super physical units, and the super physical units at least include a plurality of good super physical units and a plurality of partial good super physical units. The method includes: receiving a host write command; selecting a first super physical unit set according a number rate of the good super physical units and the partial good super physical units, and the first super physical unit set includes a plurality of first good super physical units and at least one first partial good super physical unit selected from the super physical units according to the number rate; and writing data into the good physical erasing units of the first super physical unit set, in response to the host write command.