[systemd-devel] Real Time access in a systemd control group

[Lennart Poettering]

On Fri, 29.07.11 15:50, Marius Perjeru (marius.perjeru at windriver.com) wrote:

> Hi,
> 
> We configured a systemd environment, but we cannot have real time
> access when running an application.
> 
> We have defined a xorg.service which starts the X, and every script
> runned gets under systemd/xorg.service control group, and because
> this control group does not have real time access (cpu.rt_runtime_us
> contains 0 value), we cannot run real time applications.

You have two options:

a) turn off that systemd by default adds every service into its own
cgroup in the "cpu" hierarchy. You can do this by setting
DefaultControllers= to the empty string in /etc/systemd/system.conf.

b) turn off that systemd adds the respective service (and only the
respective service) into its own cgroup, in the "cpu" hierarchy. You can
do this by setting "ControlGroup=cpu:/".

In the long run this problem while hopefully go away, when the cgroup
controller is fixed so that it doesn't require configuration of an RT
budget if we are only interested in the non-RT budget.

Lennart

-- 
Lennart Poettering - Red Hat, Inc.