On Mon, Jan 15, 2018 at 02:56:31PM +0800, Jason Wang wrote: > On 2018年01月12日 18:18, Stefan Hajnoczi wrote: > > > And what's more important, according to the kvm 2016 slides of vhost-pci, > > > the motivation of vhost-pci is not building SDN but a chain of VNFs. So > > > bypassing the central vswitch through a private VM2VM path does make > > > sense. > > > (Though whether or not vhost-pci is the best choice is still > > > questionable). > > This is probably my fault. Maybe my networking terminology is wrong. I > > consider "virtual network functions" to be part of "software-defined > > networking" use cases. I'm not implying there must be a central virtual > > switch. > > > > To rephrase: vhost-pci enables exitless VM2VM communication. > > The problem is, exitless is not what vhost-pci invents, it could be achieved > now when both sides are doing busypolling.
The only way I'm aware of is ivshmem. But ivshmem lacks a family of standard device types that allows different implementations to interoperate. We already have the virtio family of device types, so it makes sense to work on a virtio-based solution. Perhaps I've missed a different approach for exitless VM2VM communication. Please explain how VM1 and VM2 can do exitless network communication today? Also, how can VM1 provide SCSI I/O services to VM2 today? Stefan
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