tailieunhanh - SR-IOV Networking in Xen: Architecture, Design and Implementation

Consider typicalWSN applications involving the reliable de- tection and/or estimation of event features based on the collec- tive reports of several sensor nodes observing the event. Let us assume that for reliable temporal tracking, the sink must de- cide on the event features every time units. Here, represents the duration of a decision interval and is fixed by the applica- tion. At the end of each decision interval, the sink decides based on reports received from sensor nodes during that interval. The specifics of such a decision making process are application de- pendent and beyond the scope of our paper. The least we can assume is that the sink derives. | SR-IOV Networking in Xen Architecture Design and Implementation Yaozu Dong Zhao Yu and Greg Rose Abstract. SR-IOV capable network devices offer the benefits of direct I O throughput and reduced CPU utilization while greatly increasing the scalability and sharing capabilities of the device. SR-IOV allows the benefits of the paravirtualized driver s throughput increase and additional CPU usage reductions in HVMs Hardware Virtual Machines . SR-IOV uses direct I O assignment of a network device to multiple VMs maximizing the potential for using the full bandwidth capabilities of the network device as well as enabling unmodified guest OS based device drivers which will work for different underlying VMMs. Drawing on our recent experience in developing an SR-IOV capable networking solution for the Xen hypervisor we discuss the system level requirements and techniques for SR-IOV enablement on the platform. We discuss PCI configuration considerations direct MMIO interrupt handling and DMA into an HVM using an IOMMU I O Memory Management Unit . We then explain the architectural design and implementation considerations for SR-IOV networking in Xen1 in which the Physical Function has a driver running in the driver domain that serves as a master and each Virtual Function exposed to a guest VM has its own virtual driver. 1 Introduction I O is an important part of any computing platform including virtual machines running on top of a virtual machine monitor VMM such as Xen 14 11 . As has been noted many times before it s possible to have all the CPU cycles needed but if there is no data for the CPU to act upon then CPU resources are either wasted on idle cycles or in the case of software emulation of I O devices many CPU cycles are expended on I O itself reducing the amount of CPU available for processing of the data presented. For this reason much research and development has been focused on methods for reducing CPU usage for purposes of I O while increasing the amount of data .