On Wed, 27 May 2020 15:06:28 +0200 Paolo Bonzini <pbonz...@redhat.com> wrote:
> On 27/05/20 14:25, Igor Mammedov wrote: > >> (2) we loose a gigabyte page. > > I'm not sure waht exactly we loose in this case. > > Lets assume we allocating guest 5G of continuous RAM using 1G > > huge pages, > > in this case I'd think that on host side MMIO overlay won't > > affect RAM blob > > on guest side pagetables will be fragmented due to MMIO holes, > > but guest still > > could use huge pages smaller ones in fragmented area and 1G where > > there is no fragmentation. > > Access to the 3G-4G area would not be able to use 1G EPT pages. Could it use 2Mb pages instead of 1Gb? Do we really care about 1 gigabyte huge page in microvm intended usecase? (fast starting VMs for microservices like FaaS, which unlikely would use much memory to begin with) > But why use 2G split instead of 3G? There's only very little MMIO and > no PCI hole (including no huge MMCONFIG BAR) on microvm. > > Paolo >
