Issues with sudo systemctl status docker

General
1

Hello all,

I am running into some issues when running sudo systemctl status docker. I am getting the following errors:

level=warning msg="Your kernel does not support cgroup rt runtime"
level=warning msg="Your kernel does not support cgroup blkio weight"
level=warning msg="Your kernel does not support cgroup blkio weight_device"

Any help would be greatful, I am running docker in Ubuntu 18.04.5 LTS. Thanks in advance!

3

Belated answer, but looks like the Ubuntu kernel does not support the rt cgroup (for real time scheduling), and while it does support the blkio cgroup, it appears the weight and weight_device are missing.

I have Ubuntu Eoan and see something similar:

Sep 24 16:06:55 eoan dockerd[22285]: time="2020-09-24T16:06:55.765303211-07:00" level=warning msg="Your kernel does not support swap memory limit"
Sep 24 16:06:55 eoan dockerd[22285]: time="2020-09-24T16:06:55.765999749-07:00" level=warning msg="Your kernel does not support cgroup rt period"
Sep 24 16:06:55 eoan dockerd[22285]: time="2020-09-24T16:06:55.766432459-07:00" level=warning msg="Your kernel does not support cgroup rt runtime"
Sep 24 16:06:55 eoan dockerd[22285]: time="2020-09-24T16:06:55.767098539-07:00" level=warning msg="Your kernel does not support cgroup blkio weight"
Sep 24 16:06:55 eoan dockerd[22285]: time="2020-09-24T16:06:55.767616192-07:00" level=warning msg="Your kernel does not support cgroup blkio weight_device"

And looking into the blkio cgroup I don’t see the weight* files (not sure if these were removed recently):

/sys/fs/cgroup/blkio/docker$ l
total 0
--w------- 1 root root 0 Oct  9 15:21 blkio.reset_stats
-r--r--r-- 1 root root 0 Oct  9 15:21 blkio.throttle.io_service_bytes
-r--r--r-- 1 root root 0 Oct  9 15:21 blkio.throttle.io_service_bytes_recursive
-r--r--r-- 1 root root 0 Oct  9 15:21 blkio.throttle.io_serviced
-r--r--r-- 1 root root 0 Oct  9 15:21 blkio.throttle.io_serviced_recursive
-rw-r--r-- 1 root root 0 Oct  9 15:21 blkio.throttle.read_bps_device
-rw-r--r-- 1 root root 0 Oct  9 15:21 blkio.throttle.read_iops_device
-rw-r--r-- 1 root root 0 Oct  9 15:21 blkio.throttle.write_bps_device
-rw-r--r-- 1 root root 0 Oct  9 15:21 blkio.throttle.write_iops_device
drwxr-xr-x 2 root root 0 Oct  9 15:21 buildkit
-rw-r--r-- 1 root root 0 Oct  9 15:21 cgroup.clone_children
-rw-r--r-- 1 root root 0 Oct  9 15:21 cgroup.procs
-rw-r--r-- 1 root root 0 Oct  9 15:21 notify_on_release
-rw-r--r-- 1 root root 0 Oct  9 15:21 tasks
4

Thank you.
What are the impacts of lack of support for rt or weight or weight_device?

My results on Ubuntu 20.04 focal are the same for weight and weight_device, but I guess rt is available.