Windows vms shows incorrect memory usage?

[ozgurerdogan]

When I check memory usage in windows, total memory in use does not sound correct. Please see screen shot, that vm has total 20 GB Ram but windows show %85 in use which means 17 GB but if you look at processes it is not in total 17 GB. Maybe around 8-9 GB.
Using zfs..

 

[shanreich]

When you click on the Tab Performance and then select Memory, you can check whether Windows uses that RAM for caching data under the heading 'Cached'. Operating Systems use unused RAM to cache frequently used data in order to speed up the system.

 

[ozgurerdogan]

So you mean, I must also count that "Cached" amount to total ram in use?

 

[Dunuin]

Jup, RAM used for caching is still used. You can install the QEMU guest agent and then PVE will show you in its webUI cached RAM as free RAM.
Also make sure to stop a VM after changing hardware settings in case you increased that RAM recently. Otherwise the change won't take into effect, which you can see in the VMs hardware tab, when the text is written in orange.

 

[ozgurerdogan]

• Should I disable or clean occasionally (if possible), that caching ? Because it makes me think there is no enough ram on vm.
• Is this something related to ksm or balooning setting? Or only with windows?

 

[shanreich]

I'm not sure if this is even possible. I think there might be some way to do it, but if you don't want the VM to use that much RAM for caching, you could try reducing the amount of minimum RAM you provide to it and enable memory ballooning [1]. I think this would be the better solution.

The caching is only related Windows (happens on Linux as well), since it uses unused RAM for caching, which is generally a good thing. As Dunuin pointed out, you can install the QEMU guest agent, then the PVE Web UI will show the proper amount of used RAM without the cached portion.

[1] https://pve.proxmox.com/wiki/Dynami..._Windows_Server_2012_.2F_Windows_8.1_or_newer

 

[ozgurerdogan]

Just to make sure, this is not about ksm sharing ?
So can we say, if windows does not leave much free ram, instead use for caching then it thinks it is better to do so to gaster things...

 

[shanreich]

no, this is not because of KSM