Please note the official upgrade comments: https://pve.proxmox.com/wiki/Upgrade_from_8_to_9

• Official documentation: Proxmox Upgrade 8 to 9 – VM Memory Consumption Shown is Higher
• Confirmed in forum: Memory usage wrong on FreeBSD guests – 9.0.3

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.

This is a deliberate change from PVE 8, where the host-side RSS of the kvm process was shown instead.

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:

This is an open bug in FreeBSD:

• FreeBSD Bug #292570 — “virtio-balloon does not balloon correctly” (still open as of 2026)

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.

• No impact on stability or VM operation
• RAM usage in the Proxmox VE GUI and API is misleading for affected VMs
• Dynamic memory reclamation (balloon deflation) by the host does not work reliably for FreeBSD guests
• Risk of unexpected OOM conditions on the host if memory pressure is high and FreeBSD VMs cannot be deflated

• Disable ballooning for FreeBSD VMs (since it does not function correctly anyway): '# qm set <vmid> –balloon 0'
• Use proxmox-rmem — a community tool that reads guest-reported memory and surfaces it correctly: proxmox-rmem on Github
• Monitor via external tooling such as LibreNMS, Prometheus + node_exporter or Zabbix, deployed inside the FreeBSD VM
• Read actual guest memory usage via the QEMU Guest Agent (see next chapter):

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.

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:

Configuration file 'nodes/n3/qemu-server/110.conf' does not exist

Example raw output (out-data):

2018895\n15672\n64009\n123634\n1812399\n0\n4096

Calculation formulas:

• Total MB = v_page_count × v_page_size / 1024²
• Effectively used MB = (v_active_count + v_wire_count) × v_page_size / 1024² → ~544 MB (6.9%)
• Available MB = (v_free_count + v_inactive_count + v_cache_count) × v_page_size / 1024² → ~7,330 MB (92.9%)

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).

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.