Virtualization improves physical hardware utilization of cloud computing by over-committing hardware in the virtual machine. However, applications running in virtual machines suffer significant performance degradation as they do not take advantage of the features of physical hardware, which cannot be overcome by optimization of the virtual hardware. In order to reduce this performance overhead, an application virtualization mechanism is proposed to expose application instances running in the host operation system to the virtual machine, so the virtual machine can achieve optimal performance by using host instances on the real hardware. A virtio-based implementation named virtio-vapp is also proposed to show the needed adaptions. The virtio-vapp is evaluated against other communication components in Qemu to show the high load capacity and low latency of virtio-vapp. In the evaluation, virtio-vapp has a bandwidth of 36.4 Gbit/s in experiments, which is almost the same performance as the host. In addition to high load capacity and low latency, virtio-vapp supports limited migration to allow virtual machines to run applications with the same data. These results show that application virtualization can significantly reduce the performance overhead and improves flexibility and usability compared to running applications directly in the virtual machine.

Embedded and Internet of Things (IoT) devices have extremely strict requirements on the area and power consumption of the processor because of the limitation on its working environment. To reduce the overhead of the embedded processor as much as possible, this paper designs and implements a configurable 32-bit in-order RISC-V processor core based on the 16-bit data path and units, named RV16. The evaluation results show that, compared with the traditional 32-bit RISC-V processor with similar features, RV16 consumes fewer hardware resources and less power consumption. The maximum performance of RV16 running Dhrystone and CoreMark benchmarks is 0.92 DMIPS/MHz and 1.51 CoreMark/MHz, respectively, reaching 75% and 71% of traditional 32-bit processors, respectively. Moreover, a properly configured RV16 running program also consumes less energy than a traditional 32-bit processor.