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#1 2020-10-16 15:34:01

miomio
Member
Registered: 2016-01-17
Posts: 158

[SOLVED] Docker blkio.weight_device ?

New to Docker. I get the message:

Oct 16 14:47:19 neon dockerd[2242455]: time="2020-10-16T14:47:19.805910140+01:00" level=warning msg="Your kernel does not support cgroup blkio weight"
Oct 16 14:47:19 neon dockerd[2242455]: time="2020-10-16T14:47:19.805918768+01:00" level=warning msg="Your kernel does not support cgroup blkio weight_device"

So I check blkio controller is enabled (https://www.kernel.org/doc/Documentatio … roller.txt):

$ zcat /proc/config.gz | grep -i blk_cgroup
CONFIG_BLK_CGROUP=y
CONFIG_BLK_CGROUP_RWSTAT=y
CONFIG_BLK_CGROUP_IOLATENCY=y
CONFIG_BLK_CGROUP_IOCOST=y

However, looking at the thread here: https://forums.docker.com/t/issues-with … er/98564/2 a supposed solution is to do with systemd and /dev/null in the service's files, but I don't see /dev/null in mine. The second solution by user 'nestybox' is to use a realtime kernel (Ubuntu), but looking at my cgroup entries in the specified location shows 'weight_device' is present:

/sys/fs/cgroup/blkio/docker$ ls
total 0
-r--r--r-- 1 root root 0 Oct 16 16:18 blkio.bfq.io_service_bytes
-r--r--r-- 1 root root 0 Oct 16 16:18 blkio.bfq.io_service_bytes_recursive
-r--r--r-- 1 root root 0 Oct 16 16:18 blkio.bfq.io_serviced
-r--r--r-- 1 root root 0 Oct 16 16:18 blkio.bfq.io_serviced_recursive
-rw-r--r-- 1 root root 0 Oct 16 16:18 blkio.bfq.weight
-rw-r--r-- 1 root root 0 Oct 16 16:18 blkio.bfq.weight_device
--w------- 1 root root 0 Oct 16 16:18 blkio.reset_stats
-r--r--r-- 1 root root 0 Oct 16 16:18 blkio.throttle.io_service_bytes
-r--r--r-- 1 root root 0 Oct 16 16:18 blkio.throttle.io_service_bytes_recursive
-r--r--r-- 1 root root 0 Oct 16 16:18 blkio.throttle.io_serviced
-r--r--r-- 1 root root 0 Oct 16 16:18 blkio.throttle.io_serviced_recursive
-rw-r--r-- 1 root root 0 Oct 16 16:18 blkio.throttle.read_bps_device
-rw-r--r-- 1 root root 0 Oct 16 16:18 blkio.throttle.read_iops_device
-rw-r--r-- 1 root root 0 Oct 16 16:18 blkio.throttle.write_bps_device
-rw-r--r-- 1 root root 0 Oct 16 16:18 blkio.throttle.write_iops_device
-rw-r--r-- 1 root root 0 Oct 16 16:18 cgroup.clone_children
-rw-r--r-- 1 root root 0 Oct 16 16:18 cgroup.procs
-rw-r--r-- 1 root root 0 Oct 16 16:18 notify_on_release
-rw-r--r-- 1 root root 0 Oct 16 16:18 tasks

What is the solution here? Is this something that needs "fixing"?

Is it to do with cgroups, perhaps add a kernel param to load cgroups v2 (https://wiki.archlinux.org/index.php/cgroups)? Or is this an ignorable error?

Seems like Docker's Compose file format makes use of WEIGHT_DEVICE (https://docs.docker.com/compose/compose … ght_device)but Compose is "a tool for defining and running multi-container Docker applications" (https://docs.docker.com/compose/) . So unless I'm using multi-container applications I guess this is ignorable. Will I be doing that? I'm just interested in basic Docker use which to my understanding will be running some application x in a container y, so a 1-to-1 relationship rather than 1 application over multiple docker containers which sort of suggests, according to what Compose is about, a 1-to-many use-case. No?

Last edited by miomio (2020-10-16 22:20:52)

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#2 2020-10-16 15:56:26

Khere
Member
From: Italy
Registered: 2020-03-04
Posts: 62

Re: [SOLVED] Docker blkio.weight_device ?

Don't risk breaking the system for a warning


Fan of Giorgio Moroder & Mohammad Ammax enemy

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#3 2020-10-16 21:35:54

twelveeighty
Member
From: Alberta, Canada
Registered: 2011-09-04
Posts: 689

Re: [SOLVED] Docker blkio.weight_device ?

miomio wrote:

Is this something that needs "fixing"?

I wouldn't worry about it - especially if you are just getting started with Docker/containerd and don't have production-sized needs, I would just ignore that warning.

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#4 2020-10-16 22:21:14

miomio
Member
Registered: 2016-01-17
Posts: 158

Re: [SOLVED] Docker blkio.weight_device ?

Thanks both. Just a warning then and not relevant for my use case. Cheers.

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