SSD Controller Free Block List Allocation for QoS Latency
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Solution Overview
Problem
The existing SSD technologies face latency issues due to clashes between host write operations and garbage collection write operations, which occur when both operations are scheduled simultaneously for the same die, leading to suboptimal Quality of Service (QoS).
Innovation Solution
A method is introduced where a free block list is generated indicating a sequence of free super blocks, each allocated from a different die, ensuring that host write and garbage collection write operations are performed on distinct dies, thereby avoiding clashes and reducing latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If free super blocks are allocated sequentially from the same die, then allocation simplicity is maintained, but clashes between host write and garbage collection operations occur causing latency
Solution Approach 1:
The free block list is segmented by die, creating separate sub-lists for each die (e.g., first sub-list for die 0, second sub-list for die 1, third sub-list for die 2). This segmentation allows the SSD to allocate free super blocks from different dies for concurrent operations, preventing clashes between host write and garbage collection operations while maintaining organized allocation management.
2Use of energy by moving object
If host write and garbage collection operations are performed on the same die simultaneously, then resource utilization is maximized, but operation clashes occur leading to QoS degradation
Solution Approach 1:
The patent introduces a new dimension for resource allocation by organizing free blocks according to die identity. Instead of a single sequential list, the system creates multiple dimensioned sub-lists (one per die) and selects from different dimensions (different dies) to perform operations concurrently. This dimensional approach allows simultaneous host write and garbage collection operations on different dies, improving both utilization and QoS.
Data Source
AI summary
A method of operating a solid state drive (SSD) is provided. The method includes generating, by a controller provided in the SSD, a free block list indicating a plurality of free super blocks, wherein adjacent free super blocks of the plurality of free super blocks correspond to different dies of a plurality of dies provided in the SSD; and allocating, by the controller, a free super block from among the plurality of free super blocks indicated by the free block list for each of a host write operation and a garbage collection write operation, according to a sequence of the plurality of free super blocks indicated by the free block list.