On 21/09/17 10:02, Alexey Kardashevskiy wrote: > On 21/09/17 03:15, Paolo Bonzini wrote: >> On 20/09/2017 13:46, Alexey Kardashevskiy wrote: >>> Address spaces get to keep a root MR (alias or not) but FlatView stores >>> the actual MR as this is going to be used later on to decide whether to >>> share a particular FlatView or not. >>> >>> Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru> >>> --- >>> Changes: >>> v4: >>> * s/memory_region_unalias_entire/memory_region_get_flatview_root/ >> >> Did you try the idea of checking for single-child regions too? > > No, I did not, I do not see how I can actually measure the difference - the > PCI and virtio root MRs or single child MRs are unique anyway, I can save > some time by just checking for 2 @enabled flags instead of rendering a > FlatView but rendering such cases itself is fast as well. I'll give a try > though.
I tried. memory_region_get_flatview_root() returns a last child which still covers the same space as the root; generate_memory_topology() checks for @enabled first and only if it is enabled - renders a new FV (this solves PCI busmater). With 256 CPUs and 256 virtio devices this saves 0.1s (20.4s -> 20.3s) and 100MB of RAM (14.38G -> 14.28G) :) I'll push it out anyway. -- Alexey
