With some of our Lxc containers, we have observed that ct's cached memory is constantly increasing. As soon as almost the entire memory is occupied, the CPU utilisation in the container sporadically rises to 100% and the container is no longer accessible. Restarting the container (and thus clearing the cache) solves the problem.
I was also able to create the problem artificially by lowering the soft memory limit of the container during operation with:
Here, too, the CPU within the container increased to 100%, which is why I assume that this is the usual behaviour when the memory of a ct is full. However, most of the memory in the container is only occupied with cached memory, which should actually be released automatically?
The hypervisor does not have a swap partition as we use Zfs and did not want to use swap. Could there be a connection with this?
Do you have any ideas what else I could try?
I was also able to create the problem artificially by lowering the soft memory limit of the container during operation with:
Here, too, the CPU within the container increased to 100%, which is why I assume that this is the usual behaviour when the memory of a ct is full. However, most of the memory in the container is only occupied with cached memory, which should actually be released automatically?
The hypervisor does not have a swap partition as we use Zfs and did not want to use swap. Could there be a connection with this?
Do you have any ideas what else I could try?
# cat /etc/pve/lxc/123.conf
arch: amd64
cpulimit: 4
features: mknod=1,nesting=1
hostname: 123.xyz.com
memory: 6144
mp0: freenas:123/vm-123-disk-0.raw,mp=/backups,size=1000G
nameserver: 127.0.0.1
net0: name=eth0,bridge=vmbr0,firewall=1,gw=111.111.111.111,gw6=xxxx:xxxx:xxxx::x,hwaddr=BC:24:11A:CD:64,ip=111.111.111.111/24,ip6=xxxx:xxxx:xxxx/56,type=veth
onboot: 1
ostype: centos
rootfs: local-zfs2:subvol-123-disk-0,size=100G
swap: 512
unprivileged: 1
# pveversion -v
proxmox-ve: 8.4.0 (running kernel: 6.8.12-7-pve)
pve-manager: 8.4.1 (running version: 8.4.1/2a5fa54a8503f96d)
proxmox-kernel-helper: 8.1.1
proxmox-kernel-6.8: 6.8.12-9
proxmox-kernel-6.8.12-9-pve-signed: 6.8.12-9
proxmox-kernel-6.8.12-8-pve-signed: 6.8.12-8
proxmox-kernel-6.8.12-7-pve-signed: 6.8.12-7
proxmox-kernel-6.8.12-4-pve-signed: 6.8.12-4
ceph-fuse: 17.2.7-pve3
corosync: 3.1.9-pve1
criu: 3.17.1-2+deb12u1
glusterfs-client: 10.3-5
ifupdown2: 3.2.0-1+pmx11
ksm-control-daemon: 1.5-1
libjs-extjs: 7.0.0-5
libknet1: 1.30-pve2
libproxmox-acme-perl: 1.6.0
libproxmox-backup-qemu0: 1.5.1
libproxmox-rs-perl: 0.3.5
libpve-access-control: 8.2.2
libpve-apiclient-perl: 3.3.2
libpve-cluster-api-perl: 8.1.0
libpve-cluster-perl: 8.1.0
libpve-common-perl: 8.3.1
libpve-guest-common-perl: 5.2.2
libpve-http-server-perl: 5.2.2
libpve-network-perl: 0.11.2
libpve-rs-perl: 0.9.4
libpve-storage-perl: 8.3.6
libspice-server1: 0.15.1-1
lvm2: 2.03.16-2
lxc-pve: 6.0.0-1
lxcfs: 6.0.0-pve2
novnc-pve: 1.6.0-2
proxmox-backup-client: 3.4.0-1
proxmox-backup-file-restore: 3.4.0-1
proxmox-firewall: 0.7.1
proxmox-kernel-helper: 8.1.1
proxmox-mail-forward: 0.3.2
proxmox-mini-journalreader: 1.4.0
proxmox-offline-mirror-helper: 0.6.7
proxmox-widget-toolkit: 4.3.10
pve-cluster: 8.1.0
pve-container: 5.2.6
pve-docs: 8.4.0
pve-edk2-firmware: 4.2025.02-3
pve-esxi-import-tools: 0.7.3
pve-firewall: 5.1.1
pve-firmware: 3.15-3
pve-ha-manager: 4.0.7
pve-i18n: 3.4.2
pve-qemu-kvm: 9.2.0-5
pve-xtermjs: 5.5.0-2
qemu-server: 8.3.12
smartmontools: 7.3-pve1
spiceterm: 3.3.0
swtpm: 0.8.0+pve1
vncterm: 1.8.0
zfsutils-linux: 2.2.7-pve2
