On Tue, 2020-02-11 at 16:13 +0100, David Hildenbrand wrote: > >> AFAIKs, the guest could inflate/deflate (esp. temporarily) and > > > communicate via "actual" the actual balloon size as he sees it. > > > > OK so you want hinted but unused pages counted, and reported > > in "actual"? That's a vmexit before each page use ... > > No, not at all. I rather meant, that it is unclear how > inflation/deflation requests and "actual" *could* interact. Especially > if we would consider free page reporting as some way of inflation > (+immediate deflation) triggered by the guest. IMHO, we would not touch > "actual" in that case. > > But as I said, I am totally fine with keeping it as is in this patch. > IOW not glue free page reporting to inflation/deflation but let it act > like something different with its own semantics (and document these > properly). > Okay, so before I post v17 am I leaving the virtio-balloon changes as they were then? For what it is worth I agree with Michael that there is more to this than just a scatter-gather queue. For now I am trying to keep the overall impact on QEMU on the smaller side, and if we do end up supporting the MADV_FREE instead of MADV_DONTNEED that would also have an impact on things as it would be yet another difference between ballooning and hinting. Thanks. - Alex
