Re: [PATCH v33 0/4] Virtio-balloon: support free page reporting

[Michael S. Tsirkin]

On Fri, Jun 15, 2018 at 02:28:49PM +0000, Wang, Wei W wrote:
> On Friday, June 15, 2018 7:30 PM, Michael S. Tsirkin wrote:
> > On Fri, Jun 15, 2018 at 12:43:09PM +0800, Wei Wang wrote:
> > >       - remove the cmd id related interface. Now host can just send a free
> > >         page hint command to the guest (via the host_cmd config register)
> > >         to start the reporting.
> > 
> > Here we go again. And what if reporting was already started previously?
> > I don't think it's a good idea to tweak the host/guest interface yet again.
> 
> This interface is much simpler, and I'm not sure if that would be an
> issue here now, because now the guest delivers the whole buffer of
> hints to host once, instead of hint by hint as before. And the guest
> notifies host after the buffer is delivered. In any case, the host
> doorbell handler will be invoked, if host doesn't need the hints at
> that time, it will just give back the buffer. There will be no stale
> hints remained in the ring now.
> 
> Best,
> Wei

I still think all the old arguments for cmd id apply.

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MST