Messages in this thread | | | Date | Mon, 17 Aug 2009 08:54:26 -0500 | From | Anthony Liguori <> | Subject | Re: [PATCH v3 3/6] vbus: add a "vbus-proxy" bus model for vbus_driver objects |
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Ingo Molnar wrote: >> I think the reason vbus gets better performance for networking >> today is that vbus' backends are in the kernel while virtio's >> backends are currently in userspace. Since Michael has a >> functioning in-kernel backend for virtio-net now, I suspect we're >> weeks (maybe days) away from performance results. My expectation >> is that vhost + virtio-net will be as good as venet + vbus. If >> that's the case, then I don't see any reason to adopt vbus unless >> Greg things there are other compelling features over virtio. >> > > Keeping virtio's backend in user-space was rather stupid IMHO. >
I don't think it's quite so clear.
There's nothing about vhost_net that would prevent a userspace application from using it as a higher performance replacement for tun/tap.
The fact that we can avoid userspace for most of the fast paths is nice but that's really an issue of vhost_net vs. tun/tap.
From the kernel's perspective, a KVM guest is just a userspace process. Having new userspace interfaces that are only useful to KVM guests would be a bad thing.
Regards,
Anthony Liguori
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