[systemd-devel] [RFC] [PATCH] core: avoid duplicate unit property set

Lennart Poettering lennart at poettering.net
Mon Dec 8 07:08:37 PST 2014

On Mon, 08.12.14 15:12, WaLyong Cho (walyong.cho at samsung.com) wrote:

> Currently, unit property set apis set unit property and also make a
> dropin files in each dbus-xyz.c. And the dropin will set its
> properties again in unit_load().
> So don't need to set property immediatly. That will be set next
> unit_load(). Just write dropin files only.

Well, we there are two kinds of options currently:

a) the ones you can change any time, using "systemctl
   set-property". Primarily these are cgroup options to change
   resource controls during runtime. When "systemctl set-property" is
   invoked, then the changes should be instantly applied.

b) The ones you can only change when creating a transient unit, which
   cannot be changed later on with "systemctl set-property". 

Now, both kinds of properties can be set when creating transient
units, but only the properties of type (a) can be altered after
creating the units using "systemctl set-property".

Now, unit_load() is only invoked when we create units, or on
"systemctl daemon-reload". We write the drop-in snippets for these
cases. However, we also want to allow the properties of type (a) to be
effective *without* actually waiting for unit_load(), they should
apply instantly, hence we apply them also directly, without

Hope this makes sense?


Lennart Poettering, Red Hat

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