Queens steal time [nova]

Hello all, we are comparing the behavior of our queens  openstack with kilo. In queens we are observing an increase in the steal time reported in the guest along with the increase of the load averages. All this is happening while the host is not overloaded, and reports 80+ idle time Initially we have suspected that the overcommit might be the reason of the steal, so we have migrated vms, and now there are 42 vCPUs used out of the 48 pCPUs, but in the guest we still observe the steal time. with similar configuration in openstack kilo we see smaller load, and almost no steal time at all. what could be the reason of this steal time when there is no CPU overcommit? Thank you for any ideas. Kind regards, Laszlo