It's better when it's simple
Please note the official upgrade comments: https://pve.proxmox.com/wiki/Upgrade_from_8_to_9
In PVE 9, VMs that do not report memory usage via the ballooning mechanism — as well as *BSD VMs due to an incomplete balloon driver implementation — now display the host-side RAM allocation rather than the actual usage reported by the guest.
*BSD
This is a deliberate change from PVE 8, where the host-side RSS of the kvm process was shown instead.
kvm
The issue for FreeBSD is not that the balloon driver may be missing. Even if the vtballoon driver is present and active (verifiable via sysctl dev.vtballoon), the problem is more specific:
vtballoon
sysctl dev.vtballoon
VIRTIO_BALLOON_F_STATS_VQ
This is an open bug in FreeBSD:
This differs from Windows without the VirtIO BalloonService, where the driver is entirely absent. On FreeBSD, the driver exists but is functionally incomplete with respect to what Proxmox VE expects.
balloon: 0
When running FreeBSD as a Proxmox/QEMU guest with virtio-balloon enabled, the reported RAM usage in the Proxmox VE GUI is often misleading. This documents how to query actual memory usage directly from the guest using qm guest exec.
qm guest exec
Run the following on the Proxmox node where the VM resides. As an example we use an OPNsense 14.3 VM (VM ID 100) on Proxmox VE 9.1.6 (node 'n3'):
qm guest exec 100 -- sh -c "sysctl -n \ vm.stats.vm.v_page_count \ vm.stats.vm.v_active_count \ vm.stats.vm.v_inactive_count \ vm.stats.vm.v_wire_count \ vm.stats.vm.v_free_count \ vm.stats.vm.v_cache_count \ vm.stats.vm.v_page_size"
Important: Run this command on the correct node. If the VM lives on node n3, you must be logged into n3. Otherwise you will get:
n3
Configuration file 'nodes/n3/qemu-server/110.conf' does not exist
Example raw output (out-data):
out-data
2018895\n15672\n64009\n123634\n1812399\n0\n4096
Calculation formulas:
v_page_count × v_page_size / 1024²
(v_active_count + v_wire_count) × v_page_size / 1024²
(v_free_count + v_inactive_count + v_cache_count) × v_page_size / 1024²
Normally FreeBSD fills the page cache aggressively. A value of 0 for v_cache_count indicates that the virtio-balloon driver is not properly returning unused pages to the hypervisor. This is a known FreeBSD bug (FreeBSD Bug #277473).
0
v_cache_count
Proxmox derives the displayed RAM usage from the balloon driver (virtio-balloon), not from the guest agent. The balloon driver reports how much RAM the VM currently “holds” (the actual balloon value), not real consumption. This causes Proxmox to display 2–3× higher RAM usage than the guest actually needs.
actual
