Memory Device Locality Detection for NVMe Stream Identification
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Solution Overview
Problem
The NVMe standard's paired submission and completion queue mechanism complicates the detection of command streams, such as read and write streams, due to interspersion of commands from multiple queues, making it difficult to identify locality and proximity among commands.
Innovation Solution
The memory device analyzes incoming commands to determine their locality or proximity to previously assigned streams by comparing addresses or address ranges, using dynamic or static methods, and assigns them to identified streams, enabling stream detection and utilization for read look-ahead and efficient command processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the NVMe paired submission and completion queue mechanism is used, then I/O communication efficiency between host and memory device is improved, but command stream detection becomes difficult due to interspersion of commands from multiple queues
Solution Approach 1:
The patent segments the command detection process into multiple independent components: a stream detector that analyzes individual commands, a locality detector that checks address proximity, and a stream identifier that tags commands with stream information. This segmentation allows the system to handle interspersed commands from multiple queues by processing each command independently through the detection pipeline, resolving the contradiction between maintaining high I/O efficiency and enabling accurate stream detection.
Solution Approach 2:
The patent introduces an intermediary stream detection and identification mechanism that sits between the NVMe queue processing layer and the command execution layer. This intermediary component (comprising the stream detector, locality detector, and stream identifier) mediates the flow of commands, adding stream metadata without blocking the high-speed I/O path. The intermediary enables stream detection while preserving the efficient paired queue mechanism's performance characteristics.
2Productivity
If stream detection is implemented without host support, then system efficiency is improved by reducing latency and memory accesses, but device complexity increases due to additional detection and analysis mechanisms
Solution Approach 1:
The patent implements self-service stream detection where the memory device autonomously performs stream detection, locality analysis, and command tagging without requiring host software involvement. The device's internal stream detector and locality detector analyze incoming commands and self-generate stream identifiers. This self-service approach improves system efficiency by eliminating host processing overhead while the modular architecture keeps the added complexity contained within the device's existing command processing pipeline.
Solution Approach 2:
The patent designs the stream detection mechanisms to leverage existing NVMe device components for multiple purposes. The command parsing infrastructure is used both for standard NVMe command processing and for stream detection analysis. The locality detector reuses address translation and mapping hardware already present in the device. This multi-functionality approach enables sophisticated stream detection while minimizing additional device complexity by making existing components serve dual purposes.
Data Source
AI summary
Systems and methods for determining locality of an incoming command relative to previously identified write or read streams is disclosed. NVM Express (NVMe) implements a paired submission queue and completion queue mechanism, with host software on the host device placing commands into multiple submission queues. The memory device fetches the commands from the multiple submission queues, which results in the incoming commands being interspersed. In order to determine whether the incoming commands should be assigned to previously identified read or write streams, the locality of the incoming commands relative to the previously identified read or write streams is analyzed. One example of locality is proximity in address space. In response to determining locality, the incoming commands are assigned to the various streams.