/sys/fs/cgroup missing LXC relevant date after upgrade to LXC 5.0 (Debian 12)

LXC
1

Till today I used shell scripts that grep info out of /sys/fs/cgroup. Like

${LS} ${CGROUPDIR}/cpuset/lxc/*/cpuset.cpus | while read cgroupfile
do
lxc_name=echo ${cgroupfile} | $AWK -F/ '{print $7}' 2>/dev/null
lxc_cpus=${CAT} ${cgroupfile} 2>/dev/null
lxc_memory_usage=${CAT} ${CGROUPDIR}/memory/lxc/${lxc_name}/memory.usage_in_bytes 2>/dev/null
memory_usage_mb=echo ${lxc_memory_usage}/1024/1024 | ${BC} 2>/dev/null
if [ ${OPT_L} == “1” ]
then
echo -e “${lxc_name}\t${lxc_cpus}\t${memory_usage_mb}”
else
echo -n "${lxc_name} "
fi
done

Now I wanted to adapt this to LXC 5.0 where (some of) the files are in

/sys/fs/cgroup/lxc.payload.CONTAINER
/sys/fs/cgroup/lxc.monitor.CONTAINER

In this dirs all files have 0 length. Inside and outside the container. My question is why?

2

That’d be a question for the cgroup2 kernel developers as this isn’t something we have any control over.

My guess is that it’s for performance reason. All those files are virtual, so figuring out their size would require rendering them all which would be very compute intensive for no good reason.
You’ll notice the same behavior for most files in /proc and /sys.

3

where (in which forum) I can ask the cgroup2 kernel developers ?

4

Possibly the cgroups kernel development mailing list on vger.

http://vger.kernel.org/vger-lists.html#cgroups