Memory Controller Virtual Channel Priority Mapping
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Solution Overview
Problem
Current memory systems face challenges in efficiently managing communication priorities between information processing devices and nonvolatile memory systems, particularly in ensuring Quality of Service (QoS) by effectively utilizing virtual channels according to different specifications like PCIe and NVMe.
Innovation Solution
The memory system employs a controller that manages priority relation information to associate virtual channels with specific priorities, allowing communication information to be transmitted and received based on these priorities, using a combination of PCIe and NVMe specifications to optimize virtual channel usage and command processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If communication information is transmitted without priority-based virtual channel assignment, then device complexity is reduced, but Quality of Service (QoS) deteriorates
Solution Approach 1:
The communication interface is segmented into multiple virtual channels (VC0-VC7) with distinct priority levels. Each virtual channel is assigned a specific priority value (0-7), allowing communication information to be segmented and transmitted through appropriate channels based on priority requirements. This segmentation enables QoS differentiation without requiring complete redesign of the communication architecture.
Solution Approach 2:
The controller pre-establishes priority relation information that maps NVMe priority values to PCIe virtual channel identifiers before communication occurs. This preliminary assignment of priority relationships allows the system to automatically route communication information through appropriate virtual channels without real-time complex decision-making, reducing operational complexity while maintaining QoS.
2Productivity
If priority relation information is managed in the controller, then Quality of Service is improved, but device complexity increases
Solution Approach 1:
The controller pre-establishes priority relation information that maps NVMe priority values to PCIe virtual channel identifiers before communication occurs. This preliminary assignment of priority relationships allows the system to automatically route communication information through appropriate virtual channels without real-time complex decision-making, reducing operational complexity while maintaining QoS.
Solution Approach 2:
The priority relation information acts as an intermediary data structure that bridges NVMe priority values and PCIe virtual channel identifiers. This intermediary mapping table simplifies the translation process between different protocol priority systems, enabling efficient transaction processing without requiring complex real-time priority arbitration logic in the controller.
3Adaptability or versatility
If virtual channels are used according to PCIe specification, then adaptability is improved, but ease of operation deteriorates
Solution Approach 1:
The controller is designed to handle both PCIe and NVMe protocols simultaneously, with the priority relation information structure serving both specification requirements. The virtual channel assignment mechanism works universally for different types of communication information (commands, data, completions) while maintaining compliance with both PCIe and NVMe specifications, eliminating the need for separate management mechanisms.
Data Source
AI summary
According to one embodiment, a memory system includes a nonvolatile memory (NVM) and a controller. The controller communicates with an external device via virtual channels (VC) defined in PCI Express Base Specification (PCIe). The external device communicates with the NVM of the memory system per NVM Express Base Specification (NVMe). The controller manages a set of priority relation information (PRI), which maps each priority of Weighted Round Robin with Urgent Priority Class Arbitration mechanism defined in NVMe, to a specific VC. Using the PRI, the controller ensures that the same VC is used throughout the command execution transactions. Quality of Service of communication between the external device and the memory system can thus be improved.