On Wed 24-05-17 17:27:36, Mike Rapoport wrote: > On Wed, May 24, 2017 at 01:18:00PM +0200, Michal Hocko wrote: [...] > > Why cannot khugepaged simply skip over all VMAs which have userfault > > regions registered? This would sound like a less error prone approach to > > me. > > khugepaged does skip over VMAs which have userfault. We could register the > regions with userfault before populating them to avoid collapses in the > transition period.
Why cannot you register only post-copy regions and "manually" copy the pre-copy parts? > But then we'll have to populate these regions with > UFFDIO_COPY which adds quite an overhead. How big is the performance impact? -- Michal Hocko SUSE Labs
