Re: [GIT PULL] kdbus for 4.1-rc1

Richard Weinberger
2015-04-13T20:09:01Z

Am 13.04.2015 um 22:03 schrieb Greg Kroah-Hartman:
> On Mon, Apr 13, 2015 at 09:57:24PM +0200, Richard Weinberger wrote:
>>
>> Am 13.04.2015 um 21:54 schrieb Greg Kroah-Hartman:
>>> On Mon, Apr 13, 2015 at 09:49:27PM +0200, Richard Weinberger wrote:
>>>> On Mon, Apr 13, 2015 at 9:42 PM, Greg Kroah-Hartman
>>>> <gregkh@linuxfoundation.org> wrote:
>>>>>> I remain opposed to this half thought out trash of an ABI for the
>>>>>> meta-data.
>>>>>
>>>>> You don't have to enable the metadata if you don't want to use it, it's
>>>>> an option :)
>>>>
>>>> Wasn't this also an argument for CONFIG_CGROUPS?
>>>> Now we're forced to enable it by default to boot a recent distro
>>>> and CONFIG_CGROUPS is still not fixed.
>>>
>>> CONFIG_CGROUPS is "not fixed"? I think Tejun would like to have some
>>> words with you :)
>>
>> Tejun is working on it and does a *very* good job. But as long the unified
>> hirarchy is not complete/stable we're facing issues.
>> Ever tried to run systemd a linux container? ;)
>
> Works just fine for me, I do it daily. Here's how I spin up a debian
> image on my local filesystem, running systemd within it just swimmingly:
> sudo systemd-nspawn -D debian/ /sbin/init
>
> Also works just fine with gentoo and arch images, both of which I use on
> a weekly basis in this manner.
>
> Perhaps you are doing something odd that prevents this from working for
> you?

systemd-nspawn does not support user namespaces.

But the real issue is that cgroup notification does not work within namespaces.
I.e. systemd within the namespaces does not get a notify when all processes within a cgroup
are gone.
You'll notice that by running a container a long time, systemd will get slower and slower
as a lot of sessions (mostly crond) will stay.
It is known by systemd folks and I have been told that they need the new unified cgroup
hirarchy to deal with that.

I consult a lot in the linux container hosting area and had a lot of "fun" with issues like
that...

Thanks,
//richard