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12:41:52PM +0200, David Hildenbrand wrote: > > > > > > Another point in favour of COW_NOW or EAGER_COW is that we can choose to > > > allocate folios of the appropriate size at that time. Unless something's > > > changed, I think we always COW individual pages rather than multiple > > > pages at once. > > > > > > > I don't think there's any practical way to do it any differently because > > you don't know what's mapped/not at the point of fault. > > > > How expensive would it be to have xarray for anon, I wonder... :) > > We had a proposal least year I think where someone wanted to bring some > weird FreeBSD semantics into Linux MM and proposed a secondary tracking > structure for anon. Yeah ok :) you've brought the big guns out to shoot down this... well I won't say idea, cheeky thought :P It'd make some things easier, but come at a really big cost. It's obviously of great importance for the page cache (otherwise, how do you even know where anything is there). For anon this isn't the case. > > Tracking twice is obviously more expensive than tracking once, so I am quite > convinced that no, we never want that. Yup :) > > -- > Cheers > > David / dhildenb > > Cheers, Lorenzo