Virtual-Function Storage I/O Credit Scheduling for Fair Bandwidth
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Solution Overview
Problem
In SR-IOV-based I/O virtualization architectures, bandwidth resources are unevenly distributed among Virtual Function (VF) apparatuses, leading to poor quality of service and user experience, and existing solutions to balance bandwidth often incur additional hardware costs or result in resource wastage.
Innovation Solution
A storage device with a controller that initializes bandwidth credits for each VF queue based on capacity ratio and data size, dynamically scheduling I/O commands to ensure balanced distribution and prevent resource wastage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If bandwidth limiting is implemented for each VF apparatus to ensure average bandwidth distribution, then bandwidth fairness is improved, but hardware costs increase and bandwidth resources are wasted
Solution Approach 1:
The patent replaces the mechanical hardware-based bandwidth limiting system with a software/firmware-based credit management system. Instead of using physical bandwidth limiting devices and detection hardware, the controller uses virtual credit units that are allocated to each VF apparatus and consumed based on actual data transmission needs. This substitution eliminates the need for additional hardware while achieving fair bandwidth distribution through software-controlled credit allocation and consumption tracking.
2Ease of operation
If bandwidth limiting is implemented for each VF apparatus to ensure average bandwidth distribution, then bandwidth fairness is improved, but bandwidth resources are wasted
Solution Approach 1:
The patent implements dynamic bandwidth allocation through the credit mechanism. Instead of static bandwidth limits that waste resources when not fully utilized, the system dynamically adjusts bandwidth consumption based on actual credit availability and data transmission requirements. VFs can consume bandwidth up to their credit allocation, and credits are replenished based on capacity ratios, allowing the system to adapt to changing workload conditions and fully utilize available bandwidth resources without waste.
Solution Approach 2:
The patent changes the parameter of bandwidth allocation from fixed hardware limits to dynamic credit-based control. The credit allocation parameters are adjusted based on capacity ratios of different VF apparatuses, allowing flexible reconfiguration of bandwidth distribution without hardware changes. This parameter change enables the system to optimize bandwidth utilization by matching allocation to actual capacity needs rather than imposing rigid limits.
3Ease of operation
If credit-based bandwidth control is implemented, then bandwidth fairness is improved, but control complexity increases
Solution Approach 1:
The credit-based control system operates autonomously without requiring external intervention or complex centralized management. Each VF apparatus independently consumes credits based on its data transmission needs, and the controller automatically tracks credit consumption and replenishes credits according to predefined capacity ratios. This self-service mechanism simplifies control complexity by eliminating the need for continuous monitoring, manual allocation adjustments, or complex scheduling algorithms.
Data Source
AI summary
A storage device and a method performed by the same are provided in the present disclosure, the storage device including: a memory comprising a plurality of virtual function (VF) apparatuses; a controller configured to: initialize a bandwidth credit of a VF queue corresponding to each VF apparatus of the plurality of VF apparatuses; and control reading of an I/O command from the VF queue corresponding to each VF apparatus, based on the bandwidth credit and data size of the I/O command.