CSR/PDOS: Concurrent, Direct Network Access: High-performance, Low-overhead Network I/O Virtualization

支持越来越多的基于互联网的应用所带来的经济效益催生了对服务器整合的需求，从而重新燃起了人们对虚拟化的兴趣。商用硬件的虚拟化系统将处理器、内存和I/O设备虚拟化为软件。我们开发了并发直接网络访问(CDNA)，这是一种将软件和硬件结合在一起的新I/O虚拟化架构，可降低网络虚拟化的开销。此架构为不受信任的虚拟机提供对网络接口的安全、直接访问。虽然CDNA极大地提高了I/O虚拟化的效率，但本机I/O性能和虚拟I/O性能之间仍然存在显著的差距。该项目的目标是在不牺牲基于软件的I/O虚拟化的通用性和可管理性的情况下消除这种性能差距。这导致了三个主要的突破口。首先，我们正在努力减少CDNA I/O虚拟化体系结构的剩余开销，其中包括内存保护和中断调度。其次，我们正在开发支持完全虚拟化、使用IOMMU硬件的内存保护以及使用传统NIC保护的DMA的机制。这将提高CDNA I/O虚拟化体系结构的通用性。最后，我们正在开发机制，以支持在有和没有CDNA的系统之间进行迁移，并提供网络资源供应机制。这将促进使用CDNA I/O虚拟化体系结构的虚拟服务器的系统管理。总之，这项研究将使CDNA成为一个完整的I/O虚拟化解决方案，提供高效、通用和可管理的I/O虚拟化。

The economics of supporting a growing number of Internet-based applications has created a demand for server consolidation, and thus a resurgence of interest in virtualization. Virtualization systems for commodity hardware virtualize processor, memory, and I/O devices in software. Although this enables these systems to support a wide range of hardware, it also leads to significant overheads.We have developed Concurrent, Direct Network Access (CDNA), a new I/O virtualization architecture combining software and hardware that reduces the overhead of network virtualization. This architecture provides untrusted virtual machines safe, direct access to the network interface. While CDNA dramatically improves the efficiency of I/O virtualization, a notable gap between native and virtualized I/O performance still exists.This project's objective is to eliminate this performance gap without sacrificing the generality and manageability of software-based I/O virtualization. This leads to three main thrusts. First, we are working to mitigate the remaining overheads of the CDNA I/O virtualization architecture, which include memory protection and the scheduling of interrupts. Second, we are developing mechanisms to support full virtualization, memory protection using IOMMU hardware, and protected DMA by a conventional NIC. This will improve the generality of the CDNA I/O virtualization architecture. Finally, we are developing mechanisms to enable migration among systems with and without CDNA and to provide mechanisms for network resource provisioning. This will facilitate system managament for virtualized servers using the CDNA I/O virtualization architecture. Altogether, this research will make CDNA a complete I/O virtualization solution that provides efficient, general, and manageable I/O virtualization.