Abstract
With the evolution of cloud technology, the number of user applications is increasing, and computational workloads are becoming increasingly diverse and unpredictable. However, cloud data centers still exhibit a low I/O performance because of the scheduling policies employed, which are based on the degree of physical CPU (pCPU) occupancy. Notably, existing scheduling policies cannot guarantee good I/O performance because of the uncertainty of the extent of I/O occurrence and the lack of fine-grained workload classification. To overcome these limitations, we propose ISACS, an I/O strength-aware credit scheduler for virtualized environments. Based on the Credit2 scheduler, ISACS provides a fine-grained workload-aware scheduling technique to mitigate I/O performance degradation in virtualized environments. Further, ISACS uses the event channel mechanism in the virtualization architecture to expand the scope of the scheduling information area and measures the I/O strength of each virtual CPU (vCPU) in the run-queue. Then, ISACS allocates two types of virtual credits for all vCPUs in the run-queue to increase I/O performance and concurrently prevent CPU performance degradation. Finally, through I/O load balancing, ISACS prevents I/O-intensive vCPUs from becoming concentrated on specific cores. Our experiments show that compared with existing virtualization environments, ISACS provides a higher I/O performance with a negligible impact on CPU performance.
Highlights
Cloud technology is playing a crucial role in the construction of 21st Century IT infrastructure.It involves building high-performance computing resources into a virtualized environment to provide isolated computing resources in the form of virtual machines (VMs)
Our experiments show that compared with existing virtualization environments, I/O strength-aware credit scheduler (ISACS) provides a higher I/O performance with a negligible impact on CPU performance
A virtual CPU (vCPU) under the policy of two credit schedulers occupies a physical CPU (pCPU) for 30 ms or 10 ms when it is scheduled, and the credit of the vCPU is allocated or deducted according to “weight” which is a scheduling parameter that denotes the time for which the vCPU occupies the pCPU
Summary
Cloud technology is playing a crucial role in the construction of 21st Century IT infrastructure.It involves building high-performance computing resources into a virtualized environment to provide isolated computing resources in the form of virtual machines (VMs). The hypervisor scheduler, which plays a key role in managing the shared resources of a cloud server, schedules the vCPU based on the pCPU run-time of the vCPU, allowing multiple user applications to occupy the shared resources fairly. Such hypervisor scheduler policies guarantee relatively good CPU performance for CPU-intensive VMs, but are limited in terms of guaranteeing. VM has a logical driver that sends an I/O request to the backend driver of DOM0 when an I/O appears This model further simplifies the kernel code of the guest VM and enhances the security of the Xen hypervisor through I/O management based on DOM0. This section describes the important parts of the Xen architecture to elucidate ISACS
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