Messages in this thread | | | Subject | Re: [PATCH 2/2] KVM: Scalable memslots implementation | From | Paolo Bonzini <> | Date | Wed, 3 Feb 2021 15:33:38 +0100 |
| |
On 03/02/21 14:52, David Hildenbrand wrote: >> >> However, note that the TDP MMU does not need an rmap at all. Since that >> one is getting ready to become the default, the benefits of working on >> the rmap would be quite small and only affect nested virtualization. > > Right, but we currently always have to allocate it. > > 8 bytes per 4k page, 8 bytes per 2M page, 8 bytes per 1G page. > > The 4k part alone is 0.2% of the memblock size. > > For a 1 TB memslot we might "waste" > 2 GB on rmap arrays. > > (that's why I am asking :) )
Yes, we're in violent agreement. :) I mean that the simplest solution would be to allocate it lazily when building a non-TDP root.
Paolo
| |