Proxmox 5 Ballooning not working (after upgrade)

[masterdaweb]

Hello guys,

I found a bug on Proxmox 5, after upgrading. Proxmox 5 is not releasing balloning memory.

As we can see below, ballooning drivers are still working:



But that free memory is not being released to the host, that VM above just increased 12 GB on Host System total ram usage:

 

[Rhinox]

I doubt Win7/64b VM could run with just 1GB RAM used. Balooning driver could reclaim that memory, but Win7-VM would start using it immediatelly after that again...

BTW, I really do not understand this obsession of having as much free memory as possible. WHY??? Any meaninful using of memory is better, than not using it at all. You still have ~5GB free so there is no need to worry...

 

[masterdaweb]

I doubt Win7/64b VM could run with just 1GB RAM used. Balooning driver could reclaim that memory, but Win7-VM would start using it immediatelly after that again...

BTW, I really do not understand this obsession of having as much free memory as possible. WHY??? Any meaninful using of memory is better, than not using it at all. You still have ~5GB free so there is no need to worry...

The case is that there's a bug, when ballooning release memory on VM, this memory is not being released on host. It was working until I upgrade to Proxmox 5

 

[fabian]

if you think you found a bug, you should report it in our bug tracker at https://bugzilla.proxmox.com

 

[masterdaweb]

if you think you found a bug, you should report it in our bug tracker at https://bugzilla.proxmox.com

I could figure it out.

KSM-Daemon wasn't installed.

Thank you.

 

[Symbol]

I could figure it out.
KSM-Daemon wasn't installed.

But, for my understanding, what is the link between ksm (merging of identical pages on the host) and ballooning (taking back memory from guests in case of host memory pressure) ?

 

[masterdaweb]

But, for my understanding, what is the link between ksm (merging of identical pages on the host) and ballooning (taking back memory from guests in case of host memory pressure) ?

KSM daemon is responsible to take RAM back to the host when a VM releases RAM.

 

[Symbol]

KSM daemon is responsible to take RAM back to the host when a VM releases RAM.

However, I can't see that in any documentation anywhere...

 

[masterdaweb]

However, I can't see that in any documentation anywhere...

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

 

[Symbol]

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

Yes, what I meant was that I can't see the link between KSM and balloon features.

 

[fabian]

there is no connection. with KSM the host memory usage might be reduced because freed pages from different guests are merged. this is not the same as ballooning.

if you want ballooning in the sense of "dynamically change amount of memory a guest can use", you need to configure your VM as described in 10.2.5 Memory under the header "Automatic Memory Allocation". the "ballooning" option for fixed memory allocation just allows PVE to retrieve memory allocation information from inside the guest (via the ballooning device).

 

[l0rdraiden]

I might have a similar "problem" I just installed ubuntu server with mate desktop core and is taking 4.63 GB of RAM in node and VM

On top of that the VM sometimes reports 1.2 GB of RAM while in the node 4.63 GB appears.
The task manager of MATE is reporting 734MB

BTW I'm using dynamic memory.

I know that empty RAM is a waste and all that but it doesn't make sense that a light installation of ubuntu is taking more memory than a full windows 10, so if something is not working properly I would like to fix it, but I need to be pointed in the right direction.

I have 8 gb why memtotal is showing something different?
root@local:~# cat /proc/meminfo
MemTotal: 7150784 kB
MemFree: 4990416 kB
And in proxmox -> Node -> Sumary it shows that I have 6.82 in total since proxmox itsel is using 932MV without any VM running.


Thanks in advance for your help