Why my container is swapping?


Renowned Member
Oct 15, 2008
I have a container which has very slow performance, and trying to debug this i realised that it's swapping so much even if it has a lot of RAM memory available:

Screenshot 2019-06-12 at 15.09.06.png
These are the status graphs of the hypervisor:

Screenshot 2019-06-12 at 15.09.44.png
Screenshot 2019-06-12 at 15.09.37.png
Screenshot 2019-06-12 at 15.09.30.png
Screenshot 2019-06-12 at 15.09.24.png

As you can see the host does not seems to be overloaded.

Another strange thing is that the container is seeing 64 Gb of swap instead of 8:

Screenshot 2019-06-12 at 15.12.42.png

Swappiness on the host node is 0:

root@node3 ~ # cat /proc/sys/vm/swappiness

Could you help me please?
No. You'll need to implement the workaround discussed in the links I provided.

Just to be sure: are you referring to the following workaround?

ExecStartPost=/bin/find /sys/fs/cgroup -mindepth 2 -maxdepth 2 -name memory.swappiness -exec /bin/sh -c 'sysctl -n vm.swappiness > "{}"' \;
ExecStartPost=/bin/find /sys/fs/cgroup -mindepth 3 -maxdepth 3 -name memory.swappiness -exec /bin/sh -c 'sysctl -n vm.swappiness > "{}"' \;
ExecStartPost=/bin/find /sys/fs/cgroup -mindepth 4 -maxdepth 4 -name memory.swappiness -exec /bin/sh -c 'sysctl -n vm.swappiness > "{}"' \;
ExecStartPost=/bin/find /sys/fs/cgroup -mindepth 5 -maxdepth 5 -name memory.swappiness -exec /bin/sh -c 'sysctl -n vm.swappiness > "{}"' \;
ExecStartPost=/bin/find /sys/fs/cgroup -name memory.swappiness -exec /bin/sh -c 'sysctl -n vm.swappiness > "{}"' \;

Is it correct that I should apply this on the host node for Proxmox itself and containers and on VMs?

Well, that may work for you. In my case, I implemented the following on all nodes:

cat /etc/sysctl.d/local.conf

cat /etc/tmpfiles.d/mem-swap.conf
#Type Path                                              Mode UID  GID  Age Argument
w   /sys/fs/cgroup/memory/system.slice/memory.swappiness -    -    -    -   0

After rebooting each node in sequence, it resolved the problem for me. YMMV.

EDIT: systemd-tmpfiles requires a ".conf" extension or the file is ignored.
Last edited:


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