[systemd-devel] [ANNOUNCE] systemd 198

[Lennart Poettering]

On Fri, 08.03.13 10:39, Tomasz Torcz (tomek at pipebreaker.pl) wrote:

> 
> On Fri, Mar 08, 2013 at 10:26:38AM +0100, Holger Winkelmann wrote:
> > HI,
> > 
> > > >>         * Resource limits (as exposed by the various control group
> > > >>           controllers) can now be controlled dynamically at runtime
> > > >>           for all units. More specifically, you can now use a command
> > > >>           like "systemctl set-cgroup-attr foobar.service cpu.shares
> > > >>           2000" to alter the CPU shares a specific service gets. These
> > > >>           settings are stored persistently on disk, and thus allow the
> > > >>           administrator to easily adjust the resource usage of
> > > >>           services with a few simple commands. This dynamic resource
> > > >>           management logic is also available to other programs via the
> > > >>           bus. Almost any kernel cgroup attribute and controller is
> > > >>           supported.
> > > > 
> > > > Can you explain how the settings for a particular units are persistently
> > > > stored. Does systemd write back such values into the particular unit, or
> > > > are they stored somewhere else? The reason why I'm asking is the facts
> > > > that stuff like this strives the configuration management functions of
> > > > a Linux system.
> > 
> > "These settings are stored persistently on disk" goes to. If yo have such
> > setting somewhere else as back in the unit, how do you know those settings
> > exists. If they go back into the unit you obviously overwrite the bootstrap
> > default setting in the unit... may it goes into the sytemd/unite.service.d/ ?
> > 
> > Feedback would be welcome ;-)
> 
>   Runtime changes go into /run/systemd/system/<unit_id>.d/50-<unit_name>.conf; persistent
> into /etc/systemd/system/<unit_id>.d/50-<unit_name>.conf.  I'm no sure what's the
> difference between ID and name is, I'm just looking at  unit_write_drop_in() function.

Almost correct.

/{etc,run}/systemd/system/<unit_id>.d/50-<cgroup-attr-name>.conf

i.e. each attribute you set gets its own file, and can be easily reset,
simply by rm'ing that file.

Lennart

-- 
Lennart Poettering - Red Hat, Inc.