On Thursday, July 1, 2021 10:22 PM, David Hildenbrand wrote: > On 01.07.21 14:51, Peter Xu wrote: > Spoiler alert: the introduction of clean bitmaps partially broke free page > hinting > already (as clearing happens deferred -- and might never happen if we don't > migrate *any* page within a clean bitmap chunk, so pages actually remain > dirty ...). "broke" here means that pages still get migrated even though they > were reported by the guest. We'd actually not want to use clean bmaps with > free > page hinting ... long story short, free page hinting is a very fragile beast > already > and some of the hints are basically ignored and pure overhead ...
Not really. Both clear_bmap and free page hint are to "clear" the bitmap. No matter who comes first to clear it, it won’t cause more (unexpected) pages to be sent. Best, Wei
