Flash Memory Garbage Collection Dynamic Threshold Control
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Solution Overview
Problem
The garbage-collection process in FLASH memory devices is typically executed based on a single threshold value, leading to abrupt performance degradation and increased write latency, failing to adapt to varying operation statuses and host commands.
Innovation Solution
A dynamically adjusted garbage-collection process is implemented in FLASH memory devices, using multiple threshold values to determine the execution of the process, merging inefficient blocks to release spare blocks, and prioritizing performance based on different operational states and host commands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the garbage-collection process is executed based on a single threshold value, then the memory device can maintain a minimum level of efficiency, but the performance abruptly decays and write latency increases
Solution Approach 1:
The patent changes the parameter of threshold values from a single fixed value to multiple dynamic threshold values (first threshold value for inefficient blocks, second threshold value for spare blocks). This allows the garbage-collection process to be triggered at different conditions, preventing abrupt performance decay while maintaining memory efficiency through staged intervention.
Solution Approach 2:
The patent introduces dynamic adjustment of garbage-collection execution based on multiple threshold values and operational states. The system dynamically determines whether to execute garbage-collection by evaluating both the number of inefficient blocks and spare blocks against multiple thresholds, adapting the process to varying operational conditions rather than using a static single threshold.
2Reliability
If the garbage-collection process is executed frequently to maintain memory efficiency, then more spare blocks are available, but write latency increases and performance decays
Solution Approach 1:
The patent uses multiple threshold values (first threshold for inefficient blocks, second threshold for spare blocks) to control garbage-collection execution. By comparing both parameters against their respective thresholds, the system avoids unnecessary frequent executions that would increase write latency, while still maintaining memory efficiency through targeted garbage-collection at appropriate conditions.
3Device complexity
If a single threshold value is used for garbage-collection, then the control logic is simple, but the system cannot adapt to various operation statuses and host commands
Solution Approach 1:
The patent introduces multiple parameters (number of inefficient blocks, number of spare blocks, first threshold value, second threshold value) to enhance adaptability. The controller evaluates these parameters dynamically based on operation status and host commands, allowing the system to adapt to various conditions while the control logic remains structured and manageable through clear threshold comparisons.
Data Source
AI summary
A data storage device includes a FLASH memory and a controller. The FLASH memory includes a plurality of blocks wherein each of the blocks includes a plurality of pages. The controller is coupled to the FLASH memory and utilized to execute a garbage-collection process on the FLASH memory according to a number of spare blocks in the FLASH memory and a number of inefficient blocks where most of the pages are spare in the FLASH memory. The garbage-collection process is utilized for merging at least two inefficient blocks to release at least one spare block from the inefficient blocks.