Messages in this thread | | | Date | Wed, 23 Dec 2009 23:01:41 +0200 | From | Avi Kivity <> | Subject | Re: [GIT PULL] AlacrityVM guest drivers for 2.6.33 |
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On 12/23/2009 10:36 PM, Avi Kivity wrote: > On 12/23/2009 06:44 PM, Gregory Haskins wrote: >> >>> - Are a pure software concept >> By design. In fact, I would describe it as "software to software >> optimized" as opposed to trying to shoehorn into something that was >> designed as a software-to-hardware interface (and therefore has >> assumptions about the constraints in that environment that are not >> applicable in software-only). >> > > And that's the biggest mistake you can make. Look at Xen, for > instance. The paravirtualized the fork out of everything that moved > in order to get x86 virt going. And where are they now? x86_64 > syscalls are slow since they have to trap to the hypervisor and > (partially) flush the tlb. With npt or ept capable hosts performance > is better for many workloads on fullvirt. And paravirt doesn't > support Windows. Their unsung hero Jeremy is still trying to upstream > dom0 Xen support. And they get to support it forever. > > VMware stuck with the hardware defined interfaces. Sure they had to > implement binary translation to get there, but as a result, they only > have to support one interface, all guests support it, and they can > drop it on newer hosts where it doesn't give them anything.
As a twist on this, the VMware paravirt driver interface is so hardware-like that they're getting hardware vendors to supply cards that implement it. Try that with a pure software approach.
-- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain.
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