On Thu, Feb 12, 2015 at 18:03:53 +0100, Michal Privoznik wrote: > So, when building the '-numa' command line, the > qemuBuildMemoryBackendStr() function does quite a lot of checks to > chose the best backend, or to check if one is in fact needed. However, > it returned that backend is needed even for this little fella: > > <numatune> > <memory mode="strict" nodeset="0,2" /> > </numatune> > > This can be guaranteed via CGroups entirely, there's no need to use > memory-backend-ram to let qemu know where to get memory from. Well, as > long as there's no <memnode/> element, which explicitly requires the > backend. Long story short, we wouldn't have to care, as qemu works > either way. However, the problem is migration (as always). Previously, > libvirt would have started qemu with: > > -numa node,memory=X > > in this case and restricted memory placement in CGroups. Today, libvirt > creates more complicated command line: > > -object memory-backend-ram,id=ram-node0,size=X > -numa node,memdev=ram-node0 > > Again, one wouldn't find anything wrong with these two approaches. > Both work just fine. Unless you try to migrated from the older libvirt s/migrated/migrate/ > into the newer one. These two approaches are, unfortunately, not > compatible. My suggestion is, in order to allow users to migrate, lets > use the older approach for as long as the newer one is not needed. > > Signed-off-by: Michal Privoznik <mprivozn@xxxxxxxxxx> ... > diff --git a/tests/qemuxml2argvdata/qemuxml2argv-cputune-numatune.xml b/tests/qemuxml2argvdata/qemuxml2argv-cputune-numatune.xml > index 01bbb3d..fe7c465 100644 > --- a/tests/qemuxml2argvdata/qemuxml2argv-cputune-numatune.xml > +++ b/tests/qemuxml2argvdata/qemuxml2argv-cputune-numatune.xml > @@ -1,4 +1,4 @@ > -<domain type='kvm'> > +<domain type='qemu'> > <name>dummy2</name> > <uuid>4d92ec27-9ebf-400b-ae91-20c71c647c19</uuid> > <memory unit='KiB'>131072</memory> Looks like a useless change. Jirka -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list