[systemd-devel] Problem understanding output of systemd-cgtop

[Ulrich Windl]

Hi!

While examining a scheduling problem that might have resulted from restrictions imposed by cgroups, I examined my machine using systemd-cgtop and systemd-cgls (systemd-228-157.12.5.x86_64 of SLES12).
Among the things I don't understand are:
Why is systemd-cgtop outputting much less slices than systemd-cgls does? Specifically I don't see the slice for the process I'm examining ("system-iotwatch.slice"). systemd-cgls shows it with three services.

Also, when using "systemd-cgtop --depth 1", I get this output:
Control Group                            Tasks   %CPU   Memory  Input/s Output/s
/                                            -    1.1   564.7M        -        -
/init.scope                                  1      -        -        -        -
/system.slice                               82      -        -        -        -
/user.slice                                 18      -        -        -        -


Does that output mean /init.scope, /system.slice, and /user.slice all don't need any CPU and memory, while only / does?

If I don't restrict the depth, this is what I get (also when specifying a higher depth):
Control Group                            Tasks   %CPU   Memory  Input/s Output/s
/                                            -    3.5   565.8M        -        -
/init.scope                                  1      -        -        -        -
/system.slice                               82      -        -        -        -
/system.slice/auditd.service                 2      -        -        -        -
/system.slice/cron.service                   1      -        -        -        -
/system.slice/cups.service                   1      -        -        -        -
/system.slice/dbus.service                   1      -        -        -        -
/system.slice/haveged.service                1      -        -        -        -
/system.slice/icinga2.service               22      -        -        -        -
/system.slice/logd.service                   2      -        -        -        -
/system.slice/lvm2-lvmetad.service           1      -        -        -        -
/system.slice/monit.service                  2      -        -        -        -
/system.slice/nrpe.service                   1      -        -        -        -
/system.slice/nscd.service                  11      -        -        -        -
/system.slice/ntpd.service                   2      -        -        -        -
/system.slice/postfix.service                3      -        -        -        -
/system.slice/rpc-statd.service              1      -        -        -        -
/system.slice/rpcbind.service                1      -        -        -        -
/system.slice/rsyslog.service                5      -        -        -        -

So why does / have CPU and memory usage, while all others don't?

Regards,
Ulrich