CSC: Collaborative System Configuration for I/O-Intensive Applications in Multi-Tenant Clouds

I/O-intensive applications are important workloads of public clouds. Multiple cloud applications co-run on the same physical machine in different virtual machines (VMs), and the shared resources (e.g., disk bandwidth) are often isolated for fairness. Our investigation shows that the performance of an I/O-intensive application is impacted by both disk bandwidth allocation and the page cache settings in the guest operating system. However, none of prior work considers adjusting the page cache settings for better performance, when the disk bandwidth allocation is adjusted. We therefore propose CSC, a system that collaboratively identifies the appropriate disk bandwidth allocation and page cache settings in the guest operating system of each VM. CSC aims to improve the system-wide I/O throughput of the physical machine, while also improve the I/O throughput of each individual I/O-intensive application in VMs. CSC comprises an online disk bandwidth allocator and an adaptive dirty page setting optimizer. The bandwidth allocator monitors the disk bandwidth utilization and re-allocates some bandwidth from free VMs to busy VMs periodically. After the re-allocation, the optimizer identifies the appropriate dirty page settings in the guest operating system of the VMs using Bayesian Optimization. The experimental results show that CSC improves the performance of I/O-intensive applications by 9.5% on average (up to 17.29%) when 5 VMs are co-located while fairness is guaranteed.