Signed-off-by: Wei Wang <wei.w.wang@xxxxxxxxx> --- Introduction | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) create mode 100644 Introduction diff --git a/Introduction b/Introduction new file mode 100644 index 0000000..8774676 --- /dev/null +++ b/Introduction @@ -0,0 +1,31 @@ +Current vhost-user based backend designs for virtio-net devices present scaling +challenges, as communication intensive applications (e.g. virtual network +functions) running in VMs start to stress this centralized design and resources +assigned to it. + +Vhost-pci was initially proposed by Michael S. Tsirkin with vIOMMU support to +offer a protected and point-to-point based inter-VM communication. In many +cases, such as network function virtualization (NFV) and software defined +networking (SDN) usages, VMs in an isolated network trust each other and they +may be chained together to complete a task. In these use cases, people care +more about performance than security. In this RFC we present a comprehensive +design of vhost-pci without vIOMMU support. A VM with such a vhost-pci device +is able to copy data to another VM's memory directly. The advantages of using +vhost-pci over vhost-user are: 1) one less packet copy per packet transfer; and +2) better scalability. + +To follow the naming conventions in the virtio specification, we call the VM +who sends packets to the destination VM the device VM, and the VM who provides +the vring and receives packets the driver VM. The vhost-pci device/driver works +independently in the device VM. It can be considered as a simple device mapping +the entire memory of a driver VM. But a lot of times, it may be used to +communicate to a virtio device in the driver VM. That is, it usually plays the +role of a backend part of a virtio device of a driver VM. + +The vhost-pci design is not limited to networking usages. The design presented +in this RFC is quite fundamental, and it is potentially useful for other +inter-VM data moving usages. For the convenience of descriptions, we will +simply use "virtio device" to refer to the device on a driver VM that is backed +by a vhost-pci device. The figures of this RFC are shown in this link: +https://etherpad.opnfv.org/p/vhost-pci_RFC + -- 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
