Re: [GIT PULL] AlacrityVM guest drivers for 2.6.33

Gregory Haskins
2009-12-22T19:47:30Z

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On 12/22/09 2:43 PM, Avi Kivity wrote:
> On 12/22/2009 09:41 PM, Gregory Haskins wrote:
>>
>>> It means that kvm locking suddenly affects more of the kernel.
>>>
>>>
>> Thats ok. This would only be w.r.t. devices that are bound to the KVM
>> instance anyway, so they better know what they are doing (and they do).
>>
>>
>
> It's okay to the author of that device. It's not okay to the kvm
> developers who are still evolving the locking and have to handle all
> devices that use xinterface.

Perhaps, but like it or not, if you want to do in-kernel you need to
invoke backends. And if you want to invoke backends, limiting it to
thread wakeups is, well, limiting. For one, you miss out on that
exploit I mentioned earlier which can help sometimes.

Besides, the direction that Marcelo and I left the mmio/pio bus was that
it would go lockless eventually, not "more lockful" ;)

Has that changed? I honestly haven't followed whats going on in the
io-bus code in a while.

-Greg

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