Re: [libvirt] [PATCH V2] qemu: Redefine the "unlimited" memory limits one more time

On Fri, Nov 25, 2016 at 03:19:54PM +0100, Viktor Mihajlovski wrote: > On 18.11.2016 17:44, Viktor Mihajlovski wrote: > > With kernel 3.18 (since commit 3e32cb2e0a12b6915056ff04601cf1bb9b44f967) the > > "unlimited" value for cgroup memory limits has changed once again as its byte > > value is now computed from a page counter. > > The new "unlimited" value reported by the cgroup fs is therefore 2**51-1 pages > > which is (VIR_DOMAIN_MEMORY_PARAM_UNLIMITED - 3072). This results e.g. in virsh > > memtune displaying 9007199254740988 instead of unlimited for the limits. > > Ah, I wonder hoe many times we'll have to deal with this. Anyway, this means it is not enough to shift by 2 if the system hugepage is more than 4k (e.g. 2M). I remember we had to change something due to such hosts. virGetSystemPageSize(KB) should help with that. We could also make it 2^50 - pagesize just to make sure it will work for a while, but some might not like it.