Re: [PATCH] Inter-VM shared memory PCI device

Avi Kivity
2010-03-11T13:08:15Z

On 03/11/2010 02:57 PM, Arnd Bergmann wrote:
> On Thursday 11 March 2010, Avi Kivity wrote:
>
>>> A totally different option that avoids this whole problem would
>>> be to separate the signalling from the shared memory, making the
>>> PCI shared memory device a trivial device with a single memory BAR,
>>> and using something a higher-level concept like a virtio based
>>> serial line for the actual signalling.
>>>
>>>
>> That would be much slower. The current scheme allows for an
>> ioeventfd/irqfd short circuit which allows one guest to interrupt
>> another without involving their qemus at all.
>>
> Yes, the serial line approach would be much slower, but my point
> was that we can do signaling over "something else", which could
> well be something building on irqfd.
>

Well, we could, but it seems to make things more complicated? A card
with shared memory, and another card with an interrupt interconnect?

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