Ballooning seems not working properly

[banana_mcn]

Before starting the VM.


After starting the VM:
VM OS: Windows 10 (installed balloon driver and service)

The host still allocating all memory (used+unused) to it, the ballooning seems not working.



vm config

agent: 1,fstrim_cloned_disks=1
balloon: 4096
boot: order=ide0;virtio0
bootdisk: ide0
cores: 16
cpu: kvm64
cpuunits: 2
ide0: none,media=cdrom
ide1: local:iso/virtio-win.iso,media=cdrom,size=519096K
memory: 65536
meta: creation-qemu=6.2.0,ctime=1655217802
name: winh03
net0: virtio=3E:C6:2D:63:DF:FF,bridge=vmbr99
numa: 0
onboot: 1
scsihw: virtio-scsi-pci
smbios1: uuid=a457e84d-50af-44d6-b40d-7699ae68f818
sockets: 1
virtio0: P04:vm-1011-disk-0,cache=none,iops=0,mbps_rd=0,mbps_wr=0,size=500G
vmgenid: 4a60eb2c-75e8-4190-93c0-de19d3439f27

It seems the same situation with this posts but I didn't enable any PCIe passthrough.
https://forum.proxmox.com/threads/ballooning-not-working-properly.93140/

 

[datschlatscher]

I couldn't find the source post for this after a quick look anymore, but if I remember correctly, this is due to Windows mapping all the contents of its RAM at system start. The ballooning driver will only start releasing provisioned RAM when the host reaches about 80% memory usage, for your host system that should be around 100GiB.