Debian 12

apt install --no-install-recommends qemu-system libvirt-clients libvirt-daemon-system
apt install --no-install-recommends qemu-utils
apt install --no-install-recommends openvswitch-switch
apt install --no-install-recommends virtinst

Open vSwitch

ovs-vsctl add-br swglobal
ovs-vsctl add-port swglobal gateway100 tag=100 \
   -- set interface gateway100 type=internal
ovs-vsctl add-port swglobal gateway101 tag=101 \
   -- set interface gateway101 type=internal
ovs-vsctl add-port swglobal gateway102 tag=102 \
   -- set interface gateway102 type=internal

wget https://raw.githubusercontent.com/grzesieklog/unix-lab/main/hv/net/gateway

cp -v gateway /etc/network/interfaces.d/
systemctl restart networking.service

Libvirt netrowks

wget https://raw.githubusercontent.com/grzesieklog/unix-lab/main/hv/net/swglobal.xml

virsh net-define swglobal.xml
virsh net-start swglobal
virsh net-autostart swglobal
virsh net-list --all

Kernel Same-page Merging (KSM)

https://www.kernel.org/doc/Documentation/vm/ksm.txt

apt install ksmtuned

hv:~# cat /sys/kernel/mm/ksm/max_page_sharing
256
hv:~# cat /sys/kernel/mm/ksm/pages_shared
57
hv:~# cat /sys/kernel/mm/ksm/pages_sharing
3289

libguestfs

https://libguestfs.org/

apt install libguestfs-tools