With the development of virtualization technology, it is practical and necessary to integrate virtual machine software into embedded systems. I/O scheduling is important for embedded systems, because embedded systems always face different situations and their requests have more diversity on the requirement of real-time and importance. However, the semantic information associated with the I/O data is completely lost when crossing the virtualized I/O software stack. Here, we present an I/O scheduling framework to connect the semantic gap between the application threads in virtual machines and hardware schedulers in the host machine. Therefore, the details for the I/O request can be passed through the layers of the software stack and each layer can get the specific information about the device environment. Also, various scheduling points have been provided to implement different I/O strategies. Our framework was implemented based on Linux operating system, KVM, QEMU and virtio protocol. A prototype scheduler, Orthrus, was implemented to evaluate the effectiveness of the framework. Comprehensive experiments were conducted and the results show that our framework can guarantee the real-time requirements, and reserve more system resources for critical tasks, with negligible memory consumption and throughput overhead.

中文翻译：

---

用于嵌入式虚拟化的线程级 SLO 感知 I/O 框架

随着虚拟化技术的发展，将虚拟机软件集成到嵌入式系统中是现实和必要的。I/O调度对于嵌入式系统很重要，因为嵌入式系统总是面临不同的情况，他们的要求在实时性和重要性的要求上更加多样化。然而，当跨越虚拟化 I/O 软件堆栈时，与 I/O 数据相关的语义信息完全丢失。在这里，我们提出了一个 I/O 调度框架来连接虚拟机中的应用程序线程和主机中的硬件调度器之间的语义差距。因此，I/O 请求的详细信息可以通过软件堆栈的各层传递，每一层都可以获得有关设备环境的具体信息。还，提供了各种调度点来实现不同的 I/O 策略。我们的框架是基于 Linux 操作系统、KVM、QEMU 和 virtio 协议实现的。实施原型调度程序 Orthrus 来评估框架的有效性。进行了综合实验，结果表明我们的框架可以保证实时性要求，并为关键任务预留更多的系统资源，内存消耗和吞吐量开销可以忽略不计。