SSD Controller QoS Arbitration for Latency Reduction
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Solution Overview
Problem
Conventional non-volatile memory arrangements, such as solid state drives (SSDs), process commands in a serial manner, leading to suboptimal processing and increased latency, as urgent commands are often forced to wait for less urgent ones, resulting in inadequate quality of service, especially under high workloads.
Innovation Solution
Implementing a method and apparatus for SSDs that receive and order commands based on quality of service classification, using a weighted round robin algorithm to arbitrate and execute commands, ensuring that urgent operations are prioritized and completed within predefined time limits, thereby enhancing operational parameters and overall performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If commands are processed in serial format as received, then processing order is simple and device complexity is low, but latency increases and quality of service deteriorates under high workloads
Solution Approach 1:
The patent changes the processing parameter from simple serial execution to quality-of-service-based prioritized execution. Commands are classified into different QoS levels (e.g., administrative, urgent, normal, delayed) and processed according to their classification rather than arrival order, reducing latency for critical commands while managing overall system complexity through structured arbitration
Solution Approach 2:
The command stream is segmented into multiple QoS categories (administrative, urgent, normal, delayed), allowing different segments to be processed in different priority queues. This segmentation enables urgent commands to be handled separately from normal commands, reducing their latency without affecting overall system operation
2Reliability
If urgent commands are placed in the same queue as normal commands, then queue management is simple, but urgent commands may be forced to wait and quality of service is inadequate
Solution Approach 1:
Multiple separate queues are created for different QoS levels (administrative queue, urgent queue, normal queue, delayed queue). Each queue manages commands of similar priority, ensuring urgent commands are never blocked by normal commands. This segmentation improves reliability of service delivery while keeping individual queue management relatively simple
Solution Approach 2:
A QoS classification mechanism acts as an intermediary between command submission and execution. Commands are classified and routed to appropriate queues based on their QoS requirements, ensuring proper prioritization without requiring complex real-time arbitration during execution
3Speed
If all commands are processed equally without prioritization, then processing is fair and simple, but latency is high for time-sensitive operations
Solution Approach 1:
The processing speed parameter is enhanced by introducing QoS-based priority levels. Administrative and urgent commands are assigned higher priority parameters that ensure they are selected for execution first, achieving faster processing speeds for time-sensitive operations while maintaining a manageable arbitration structure
Data Source
AI summary
A method and apparatus for operating a solid state drive is disclosed comprising receiving at least two commands from a host requiring an action by the solid state drive in a preliminary order, ordering the at least two commands based upon a quality of service classification for the at least two commands to a final order and executing the at least two commands on the solid state drive in the final order, wherein an operational parameter of the solid state drive is modified by at least one of the at least two commands.