On Thu, Jan 09, 2020 at 02:00:00PM +0100, Vitaly Kuznetsov wrote: > "Dr. David Alan Gilbert" <dgilb...@redhat.com> writes: > > > And I think vhost-user will fail if you have too many sections - and > > the 16 sections from synic I think will blow the slots available. > > > > SynIC is percpu, it will allocate two 4k pages for every vCPU the guest > has so we're potentially looking at hundreds of such regions.
Indeed. I think my original idea to implement overlay pages word-for-word to the HyperV spec was a mistake, as it lead to fragmentation and memslot waste. I'll look into reworking it without actually mapping extra pages over the existing RAM, but achieving overlay semantics by just shoving the *content* of the "overlaid" memory somewhere. That said, I haven't yet fully understood how the reported issue came about, and thus whether the proposed approach would resolve it too. Thanks, Roman.