Memory not returned on Windows when running ballooning.

[dorbeus]

After updating to pve 9 several windows vms stared to experience this issue, not all.

The memory usage of the affected VMs slowly increased, it was shown in the Proxmox graphs.
This was also shown Windows Task Manager however there is no processes using the memory.
Have updated the virtio drivers.

When memory usage approached 100% it started to swapping and CPU load increased significantly.

After setting the min max memory to the same value, the memory was immediately released and became available to the VM again.

This suggest that there is a problem with the memory ballooning.

 

[templar]

I've had problem with this:

Note that if you are passing through a physical PCI(e) device or a Virtual Function I/O (VFIO) Mediated device (MDEV) such as a vGPU, then ballooning will not work since these devices are mapped to fixed memory addresses in the host and in the guest. If you do enable ballooning, the KVM process will not release the memory back to the host but the guest may report a reduced memory availability which can be manually recovered using the KVM monitor using the balloon command.

https://pve.proxmox.com/wiki/Dynamic_Memory_Management#Ballooning