AFAIK bhyve does not have the possibility (like kvm or virtualbox) to cap the physical core count independent of virtual number chosen.
Perhaps you could downscale the 4core VM to 2 cores (leaving at least 2 for handling sysio) and see if this helps prevent your problem. At least this would confirm the overcommit is part of the problem or whether this is just haunting a ghost.
Can't really advise you on further tuning of bhyve - there might be a way (-p option, -H option) to forcibly hold all your VM's to a limited number of cores. Even my previous advice might be too conservative.
bhyve gurus : please step in!
Perhaps you could downscale the 4core VM to 2 cores (leaving at least 2 for handling sysio) and see if this helps prevent your problem. At least this would confirm the overcommit is part of the problem or whether this is just haunting a ghost.
Can't really advise you on further tuning of bhyve - there might be a way (-p option, -H option) to forcibly hold all your VM's to a limited number of cores. Even my previous advice might be too conservative.
bhyve gurus : please step in!