[CRIU] [PATCH 2/2] cg: Add ability to dump custom cgroup properties

[Cyrill Gorcunov]

On Fri, Apr 15, 2016 at 03:26:05PM +0300, Pavel Emelyanov wrote:
> On 04/14/2016 05:41 PM, Tycho Andersen wrote:
> > Hi Cyrill,
> > 
> > On Tue, Apr 12, 2016 at 12:40:40PM +0300, Cyrill Gorcunov wrote:
> >> We have some common predefined properties such as
> >> "cpuset.cpus" and etc gathered in @cgp_predefined
> >> set, but there might be situation when only predefined
> >> ones are not enough so add ability to specify additional
> >> properties via --cgroup-props option.
> >>
> >> This option takes either path to a file or plain JSON
> >> stream which describe the properties to dump.
> >>
> >> For example one may pass
> >>
> >>   --cgroup-props "{\"controller name 1\" : [ \"property-1\", \"property-2\", ... ]}"
> >>
> >> to dump custom properties.
> >>
> >> At moment we require Jansson library to be present in the
> >> system to support JSON parsing of --cgroup-props. But if
> >> someone doesn't need custom properties lets don't force
> >> him to setup Jansson library for nothing, simply compile
> >> criu without this feature support.
> > 
> > Not related to this patch, but it seems like I've let the list of
> > predefined properties get fairly out of date (e.g. the entire pids
> > cgroups, and a bunch of others are missing). It seems to me like we
> > should have CRIU have a reasonably comprehensive list of cgroup props,
> > and then leave this for other stuff (like custom cgroups in the vz
> > kernel or whatever). Does that make sense?
> 
> It does, but do you have any ideas how to keep this list up-to-date 
> without recompiling criu for every new property? %)

With custom cgroups engine one simply need to pass JSON file with
descriptor and criu will replace predefined cgroups.