[systemd-devel] Real-time permission affected by root login on other tty

[Lars Christensen]

On Sun, Mar 8, 2015 at 11:27 PM, Lennart Poettering
<lennart at poettering.net> wrote:
> Most likely you have RT cgroup scheduling enabled in the kernel, and
> some unit uses CPUShares=, CPUAccounting=, CPUQuota*= in the unit
> file. If a unit does that this will move the unit's cgroup into the
> "cpu" cgroup controller, as well as all its parent and sibling cgroups
> (and thus units).

I can only find a commented out CPUAccounting= in
/etc/systemd/system.conf. No other configuration file mention the
above parameters. I'm on a fresh install of Arch.

> When a process is in a cgroup in the "cpu" controller, and no RT
> budget is set for that cgroup, then RT is not available to it. This is
> very unfortunate. I'd love to assign an RT budget by default from
> systmed, but this isn't really doable, since there's no sane RT budget
> one could assign a cgroup given the current semantics of it (which
> require that all RT budgets of cgroups within another cgroup must sum
> up to less than 1/1...).

Here's the output of /proc/self/cgroup when logging in as non-root
user while root is logged in other vconsole or via ssh:

8:memory:/user.slice/user-1000.slice
7:blkio:/user.slice/user-1000.slice
6:cpuset:/
5:cpu,cpuacct:/user.slice/user-1000.slice
4:devices:/user.slice/user-1000.slice
3:net_cls:/
2:freezer:/
1:name=systemd:/user.slice/user-1000.slice/session-c3.scope

When logging in as non-root alone, or when downgrading to systemd-216:

8:memory:/
7:blkio:/
6:cpuset:/
5:cpu,cpuacct:/
4:devices:/
3:net_cls:/
2:freezer:/
1:name=systemd:/user.slice/user-1000.slice/session-c1.scope

-- 
Lars