How to configure dockerd not to use some specific cpus?

all.

I want to reserve some cpus for realtime task. I tried to use cset utility,(https://github.com/lpechacek/cpuset/blob/master/doc/tutorial.txt) but failed since dockerd reserve all available cpu to its own cpuset.

Then, I reserved cpus 0~11 using cset shield --cpus 0-10 command before launching dockerd. But it didn't work either. cpus were shielded and dockerd was launched but couldn't start containers:

2021-07-19T17:11:13+09:00 myserver dockerd[59166]: time="2021-07-
19T17:11:13.267579743+09:00" level=error msg="fatal task error"
error="starting container failed: OCI runtime create failed:
container_linux.go:367: starting container process caused:
process_linux.go:340: applying cgroup configuration for process caused:
failed to write \"0-79\\n\": write /sys/fs/cgroup/cpuset/docker/cpuset.cpus:
invalid argument: unknown" module=node/agent/taskmanager 
node.id=rzeijp8jgedezsli9x4ftjugc service.id=z6cz3jtf6nz4293ye50l23f2o 
task.id=qn9zcc45rvjdk50jyaycri7lg

The cset result says cpuset gets conflict:

# cset set --list
cset: 
     Name       CPUs-X    MEMs-X Tasks Subs Path
 ------------ ---------- - ------- - ----- ---- ----------
     root       0-79 y     0-1 y   696    3 /
   docker      ***** n   ***** n     0    0 /docker
   system      12-79 y       0 n   481    0 /system
     user       0-11 y       0 n     0    0 /user

I guess that I need to tell dockerd not to use reserved cpus for its cpuset but cannot find how.

Any comments or suggestions will be appreciated deeply.

Solution

We can set dockerd configuration to /etc/docker/daemon.json. I set parent cgroup of docker to /system and the problem solved:

# cat /etc/docker/daemon.json 
{
  "cgroup-parent": "/system"
}