Proxmox memory usage questions with LXC

[deniax]

Hi,

I have two questions based on the attached screenshot:

1) My LXC container runs out of memory and becomes almost unresponsive because of that. The memory reportage in Proxmox seems correct as in screenshot its seen that from the total 41GB of memory, whilst 0 is free, there's 36GB in cache, meaning the reported 4.41GB in use is correct.

I'm writing to RAM (/dev/shm) , but why is it showing me that there is still 30GB of memory free/available when there's clearly not

root@ibra:/opt/appdata/bazarr# df -H
Filesystem                        Size  Used Avail Use% Mounted on
/dev/mapper/ssd-vm--102--disk--0   64G   49G   12G  81% /
/dev/mapper/ssd-vm--102--disk--1  270G   33k  256G   1% /ssd
none                              504k  4.1k  500k   1% /dev
tmpfs                              68G   39G   30G  57% /dev/shm

And also why the LXC container becomes for 95% unresponsive and it doesn't use it "data in cache" which is 36GB? Or maybe thats more a question for Ubuntu that I'm running?

2) Why If I have configured 40GB of SWAP configured in Proxmox, the LXC container shows I have 8GB of swap?

 

[Matthias.]

Some distros (e.g. alpine) seem to have version of free/top/... that show the swap/memory info from the host, and some (e.g. debian) the memory assigned to the lxc.

 

[deniax]

Some distros (e.g. alpine) seem to have version of free/top/... that show the swap/memory info from the host, and some (e.g. debian) the memory assigned to the lxc.

Thanks.
I installed from the Proxmox template Debian 11/bullseye , and indeed the memory is now correct, but the SWAP seems still to be ignored, I set 39.5GB in Proxmox , but Debian LXC reports only 8.1GB (see screenshot)

 

[Matthias.]

Our docs 11.4.3. Memory https://pve.proxmox.com/pve-docs/pve-admin-guide.html#pct_settings say you can only use swap from the host space
In other words (but without having looked at the implementation), the upper bound for the swap in the container is the host swap size

 

[deniax]

Ah ok, thanks, yes this is the case here as well! Thank you for clearing it up