Ubuntu 20 VM and memory!

[Gilberto Ferreira]

Hello there.
I don't know if this is a bug in Ubuntu of Proxmox VE.
I have a VM with Ubuntu 20 and for some reason, the total memory is show up wrong.
I have baloon activated and qemu guest as well.
I have hotplug activated too.
Tha default Linux Kernel which came with Ubuntu 20 doesn't display the right total memory. Instead just show sometimes 4 or 5G, but in the VM configuration I have set it to 8 or 16G.
The only kernel which seems to work fine is 5.8.0-63-generic.
Heres's some configuration:
Ubuntu 20
5.8.0-63-generic

PVE Manager Version pve-manager/7.2-7/d0dd0e85
Linux 5.13.19-2-pve

qm conf 189
agent: 1
balloon: 1024
boot: order=scsi0
cores: 16
cpu: qemu64
hotplug: disk,network,usb,memory,cpu
ide2: none,media=cdrom
memory: 16384
meta: creation-qemu=6.1.0,ctime=1659636189
name: cliente-V-IP-6-18
net0: virtio=76:93:C1:78:03:F7,bridge=vmbr0,firewall=1
numa: 1
onboot: 1
ostype: l26
scsi0: local-lvm:vm-189-disk-0,cache=writeback,discard=on,iothread=1,size=100G,ssd=1
scsihw: virtio-scsi-pci
smbios1: uuid=b6edf3f2-f08d-445b-83df-34d5d2f5aa28
sockets: 2
vcpus: 8
vmgenid: fd45c674-c523-4cb2-9478-503052489a4b

 

[leesteken]

Inside the VM Ubuntu will show between 1GB (minimum memory setting) and 16GB (memory setting), depending on how much memory is taken away from the VM due to ballooning.

 

[Gilberto Ferreira]

Inside the VM Ubuntu will show between 1GB (minimum memory setting) and 16GB (memory setting), depending on how much memory is taken away from the VM due to ballooning.

Yeah! I realize that.
But to the customer this is awful, 'cause he bought a VPS with 8G and now there is only 1G showing up????
On the other hand, leave the vm without balloon could be not a good idea with dozen of VMs!
But i see you point.

 

[leesteken]

But to the customer this is awful, 'cause he bought a VPS with 8G and now there is only 1G showing up????
On the other hand, leave the vm without balloon could be not a good idea with dozen of VMs!

The inside of a VM has no influence what so ever on the ballooning, it depends on the other VMs and Proxmox. Maybe that's not something you want to exposes to the user? Overcommit of memory (and swapping VM memory) does not really work for anyone, as far as I know.

 

[Dunuin]

The inside of a VM has no influence what so ever on the ballooning, it depends on the other VMs and Proxmox. Maybe that's not something you want to exposes to the user? Overcommit of memory (and swapping VM memory) does not really work for anyone, as far as I know.

Fully agree. If you are selling a VM with 8GB RAM your ballooning should be set to atleast "Minimum RAM: 8GB" so that the customer always got atleast that much of RAM without ballooning killing the customers services because you overcommit RAM. Otherwise there is nothing preventing PVE from reducing the guest RAM down to 1GB with your "Minimum RAM: 1GB" setting so that the guest OS just will kill enough processes until memory usage is down to 1GB.

 

[Gilberto Ferreira]

Fully agree. If you are selling a VM with 8GB RAM your ballooning should be set to atleast "Minimum RAM: 8GB" so that the customer always got atleast that much of RAM without ballooning killing the customers services because you overcommit RAM. Otherwise there is nothing preventing PVE from reducing the guest RAM down to 1GB with your "Minimum RAM: 1GB" setting so that the guest OS just will kill enough processes until memory usage is down to 1GB.

Yes. This is right. I will review the policies for this services.
Thanks guys.