User-Space NVMe Queue Access via Direct Register Mapping
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Solution Overview
Problem
Existing NVMe device access through kernel software layers incurs high latency and overhead due to context switches and buffer copies, limiting performance and flexibility in accessing non-volatile memory express (NVMe) devices.
Innovation Solution
Mapping NVMe device registers, including doorbell registers, directly to user space virtual memory using a stride parameter to bypass kernel layers, allowing direct access and increased parallelism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If NVMe devices are accessed through kernel software layers, then device management and control are maintained, but access latency increases and performance decreases due to context switches and buffer copies
Solution Approach 1:
The patent segments the access path by creating a direct user-space interface to NVMe device registers, separating the high-level kernel management functions from the low-level device access operations. This allows most operations to bypass the kernel while maintaining kernel control for critical functions.
Solution Approach 2:
The patent introduces an intermediary mechanism (user-space driver with direct register mapping) that mediates between applications and the NVMe device, eliminating the need for kernel-space intermediaries and their associated context switches and buffer copies.
2Stability of the object's composition
If NVMe devices are accessed through kernel software layers, then system stability is maintained, but throughput is limited due to overhead from context switches and buffer copies
Solution Approach 1:
The patent extracts the device access functionality from the kernel space and places it in user space, removing the overhead of context switches and buffer copies while maintaining system stability through careful design of the user-space interface.
3Speed
If registers are mapped directly to user space virtual memory, then access speed and throughput improve, but system complexity increases due to direct memory mapping requirements
Solution Approach 1:
The patent changes the memory mapping parameters by using stride parameters to control the mapping of device registers to user-space virtual memory, allowing flexible configuration of register access patterns while maintaining direct access performance.
4Adaptability or versatility
If stride parameter is used to map registers to user space, then access flexibility and customization improve, but mapping complexity increases
Solution Approach 1:
The patent makes the register mapping dynamic and configurable through stride parameters, allowing the system to adapt to different access patterns and performance requirements while providing a programmable interface for optimization.
Data Source
AI summary
An embodiment includes a system, comprising: a processor configured to: read a stride parameter from a device coupled to the processor; and map registers associated with the device into virtual memory based on the stride parameter; wherein: the stride parameter is configured to indicate a stride between the registers associated with the device; and the processor is configured to map at least one of the registers to user space virtual memory in response to the stride parameter.