Re: [GIT PULL] AlacrityVM guest drivers for 2.6.33

Gregory Haskins
2009-12-24T09:31:18Z

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On 12/23/09 3:36 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.

Sorry, that is just wrong or you wouldn't have virtio either.

> 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.

We are only talking about PV-IO here, so not apples to apples to what
Xen is going through.

>
> 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.

Again, you are confusing PV-IO. Not relevant here. Afaict, vmware,
kvm, xen, etc, all still do PV-IO and likely will for the foreseeable
future.

-Greg

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