On 11.07.2018 17:07, frankja wrote: > On Fri, 6 Jul 2018 16:52:50 +0200 > David Hildenbrand <david@xxxxxxxxxx> wrote: > >> On 06.07.2018 15:55, Janosch Frank wrote: >>> So, after the userfaultfd fix postcopy does work now, but vSIE in >>> combination with paging can still result in crashing g3s. Therefore >>> we split up the series and only integrate non-vSIE support for now. >>> >> >> Just for the fun of it, did you try unlocking THP on a 4k guest with >> the KVM huge page capability set? Should be fairly easy. >> >> My assumption is that it should be a pretty good sanity check if all >> notifiers/invalidations are working :) > > After ripping out all of the safeguards, the guest boots and is > successfully running memtester on 4g of its memory. > > The guest itself has 6gb: > > 3fdeff00000-3ff6ff00000 rw-p 00000000 00:00 0 > Size: 6291456 kB > KernelPageSize: 4 kB > MMUPageSize: 4 kB > Rss: 6291456 kB > Pss: 6291456 kB > Shared_Clean: 0 kB > Shared_Dirty: 0 kB > Private_Clean: 0 kB > Private_Dirty: 6291456 kB > Referenced: 6291456 kB > Anonymous: 6291456 kB > LazyFree: 0 kB > AnonHugePages: 6266880 kB > ShmemPmdMapped: 0 kB > Shared_Hugetlb: 0 kB > Private_Hugetlb: 0 kB > Swap: 0 kB > SwapPss: 0 kB > Locked: 6291456 kB > VmFlags: rd wr mr mw me dc ac dd hg mg > Well that looks promising. Does it make sense to add that "unlocking" as an addon patch right away? So if - KVM module is loaded with the right module parameter - QEMU does not enable CMMA and sets the HPAGE KVM capability Transparent huge pages would be used. It could be in QEMU as simple as "if CMM CPU feature is not enabled, HPAGE capability will be set if available". So "-cpu host" will behave as before. "-cpu host,cmm=off" would result in THP being used (if KVM supports HPAGE capability). Migration should work out of the box. Opinions? -- Thanks, David / dhildenb
