虛擬化技術(shù)virtualizationtechniques-文庫(kù)吧資料
2025-07-27 10:02本頁(yè)面
【正文】 ance performance) ? C – Directed I/O and Device Sharing (resource saving) Virtual Machine Virtual Machine I/O Driver Virtual Machine I/O Driver Virtual Machine Monitor Virtual Machine I/O Driver Virtual Machine I/O Driver Virtual Machine Monitor Virtual Machine I/O Driver Virtual Machine I/O Driver Virtual Machine Monitor Virtual Function Physical Function A – Software only B – Directed I/O C – Directed I/O amp。 Device Sharing PCIE I/O VIRTUALIZATION Motivation Directed I/O PCIe Architecture Directed I/O ? Softwarebased sharing adds overhead to each I/O due to emulation layer ? This indirection has the additional affect of eliminating the use of hardware acceleration that may be available in the physical device. ? Directed I/O has added enhancements to facilitate memory translation and ensure protection of memory that enables a device to directly DMA to/form host memory. ? Bypass the VMM’s I/O emulation layer ? Throughput improvement for the VMs Drawbacks to Directed I/O ? One concern with direct assignment is that it has limited scalability ? A physical device can only be assigned to one VM. ? For example, a dual port NIC allows for direct assignment to two VMs. (one port per VM) ? Consider for a moment a fairly substantial server of the very near future ? 4 physical CPU’s ? 12 cores per CPU ? If we use the rule that one VM per core, it would need 48 physical ports. Terminology relating to Directed I/O Acronym Expansion Defined By What is it? I/O MMU I/O Memory Management Unit Common parlance Translation mechanism in the system memory controller (North Bridge) that allows a device or set of devices to use translated addresses when accessing main memory. In many cases, it also translates interrupts ing from the devices as messages. ATPT Address Translation and Protection Table PCI SIG I/O MMU VTd, VTd2 Virtualization Technology for Directed I/O Intel I/O MMU DMAr DMA Remapping Intel, Microsoft I/O MMU IOMMU I/O Memory Management Unit AMD I/O MMU PCIE I/O VIRTUALIZATION Motivation Directed I/O PCIe Architecture Generic Platform ? System Image(SI) ? SW, ., a guest OS, to which virtual and physical devices can be assigned System Image (SI) Processor Memory Root Complex (RC) Root Port (RP) Root Port (RP) PCIe Device Switch PCIe Device PCIe Device PCIe Device System Image (SI) System Image (SI) System Image (SI) Virtualization Intermediary PCIe ponents ? Root Complex ? A root plex connects the processor and memory subsystem to the PCIe switch fabric posed of one or more switch devices ? Similar to a host bridge in a PCI system ? Generate transaction requests on behalf of the processor, which is interconnected through a local bus. ? May contain more than one PCIe port and multiple switch devices. PCIe ponents ? Root Port (RP) ? The portion of the mothe
環(huán)評(píng)公示相關(guān)推薦
鄂ICP備17016276號(hào)-1