systemd, logind, upstart, wayland, weston chat at Munich BSP

[Saurabh Chopra]

hi,

-I have been a part of the community from a round 3-4 months, and have an
experience working on Cgroups on embedded systems form past 10 months.
-Would like to contribute to KDE.
-Much appreciated if guided about the tasks.

Thanx

Saurabh Chopra


On Mon, Nov 25, 2013 at 4:48 PM, Àlex Fiestas <afiestas at kde.org> wrote:

> On Saturday 23 November 2013 15:27:44 Jonathan Riddell wrote:
> > We chatted a bit about this topics at Munich BSP
> >
> > without Mir or Plasma 2 to worry about in this cycle there's no immediate
> > issues but we need to keep an eye on them
> >
> > cgroups (control groups) is a feature of Linux to limit, account and
> > isolate resource usage (CPU, memory, disk I/O, etc.) of process groups.
> > this is used in logind to get the system compositor without privilages
> > which is needed by kwin.  so kwin will probably need an init system with
> > cgroup support.  fortunately I see plans are under way for this in
> upstart
> >
> https://lists.ubuntu.com/archives/upstart-devel/2013-November/002942.html
>
> CGroups by default only group processes and their children and no policy is
> applied.
>
> For example, this will allow us to spawn N nepomuk index processes and keep
> track of them since all of them will be in the same cgroup.
>
> Then, you can enable "subsystems" that make use of these cgroups in a
> particular way, for example given a certain amount of resources, or giving
> them special access to a certain device.
>
> More about cgroups here:
> https://www.kernel.org/doc/Documentation/cgroups/cgroups.txt
>
> > the current version of logind in ubuntu is not enough for wayland because
> > it needs to get special access to hardware for compositing (which it does
> > through cgroups) so we will need an updated version of logind at some
> > point.  but that's hard because logind is now inseperable from systemd.
> Systemd and logind are developed as a whole, so application developers will
> use systemd interfaces while working with logind.
>
> One example is in PowerDevil, we check the version of systemd to know what
> features are available (and work) on logind, things like
> suspend/hibernate/inhibition... That call to check the version is not even
> implemented in systemd-shim (the systemd emulation Ubuntu uses), and we
> had to
> add a workaround for Kubuntu days before the release.
>
> So even if Ubuntu developers "strip' a new logind version for 14.04, that
> doesn't mean that all applications depending on logind1 will work well.
>
> > afiestas has started working on looking at using systemd for KDE Plasma
> > startup, this should have a magic export to make a simple script to start
> > up if you don't use systemd but it won't be as fast.
> This only relates to the startup, systemd will affect other things.
>
> > So no easy answers yet, lots happening in the future we should keep an
> eye
> > on.
>
> There are things to do right now, we should:
> -Get knowledge of how upstart works, so we can add support in KDE for it.
> -Track all programs using systemd, make sure that them work with the fake
> Ubuntu implementation and the "stripped" logind1 (PowerDevil, user-manager,
> DM, logout/switch user/...)
> -Before beta of 4.12, 4.13, 5.0... Make sure everything works, track what
> new
> dependencies have been added to systemd etc.
>
> Basically, as long as Ubuntu uses forks and weird versions of systemd,
> Kubuntu
> should focus on making sure all the software works.
>
> Maybe we can start with a list of programs using
> systemd/logind/dated/hostnamed.... and add them to the list of things to
> test.
>
> Cheers !
>
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