Memory Controller Credit-Based Rate Control for Bursty Completions
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Solution Overview
Problem
Memory systems, such as enterprise SSDs, face inconsistent performance metrics due to bursty command processing completions, leading to variability in throughput and latency, which affects quality of service and consistency over time.
Innovation Solution
Implementing a credit-based rate control mechanism in the memory system's controller to manage the completion notification rate of commands across time intervals, ensuring consistent throughput and reduced latency by redistributing bursty completions and adjusting throughput credits based on target performance metrics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If bursty command processing completions are allowed to proceed naturally, then processing speed is improved, but throughput consistency deteriorates
Solution Approach 1:
The patent applies periodic action by using time intervals to regulate completion notifications. The controller determines a number of completion notifications to transmit within each time interval based on throughput credit, creating a periodic control mechanism that smooths bursty completions while maintaining processing speed.
Solution Approach 2:
The patent changes the parameter of completion notification rate by using throughput credit to dynamically adjust the number of notifications transmitted per time interval. This parameter change transforms bursty completions into a regulated stream, achieving both speed and consistency.
2Productivity
If completion notifications are transmitted at high rate, then productivity is improved, but latency variability worsens
Solution Approach 1:
The patent changes the transmission rate parameter of completion notifications by using throughput credit to control the number of notifications per time interval. This dynamic parameter adjustment maintains high productivity while reducing latency variability through regulated transmission.
Solution Approach 2:
The patent ensures continuity of useful action by maintaining a steady stream of completion notifications through credit-based regulation. Instead of allowing bursty interruptions, the system maintains continuous regulated transmission, improving latency predictability while preserving overall productivity.
3Stability of the object's composition
If throughput credit is used to regulate completion notifications, then throughput consistency is improved, but system complexity increases
Solution Approach 1:
The patent uses feedback by monitoring completion notifications and adjusting throughput credit accordingly. The controller determines the number of notifications to transmit based on current credit status, creating a feedback loop that maintains throughput consistency without requiring complex external control systems.
Data Source
AI summary
A controller of a memory system controls a completion rate of commands. The controller receives, from a host, command requests to be processed on a memory device. The controller processes the command requests, determines a first number of completion notifications, which are to be transmitted to the host in a first time interval, among multiple completion notifications associated with the command requests, based on a throughput credit, a set maximum credit, and the number of the multiple completion notifications. The controller transmits, to the host, the first number of completion notifications in the first time interval, and transmits a second number of completion notifications in the second time interval.