[systemd-devel] [PATCH v2] cgroup-util: fix is_valid check to pass for unified cgroup hierchy.
Dimitri John Ledkov
dimitri.j.ledkov at intel.com
Fri May 29 07:52:50 PDT 2015
On 29 May 2015 at 14:41, Lennart Poettering <lennart at poettering.net> wrote:
> On Fri, 29.05.15 12:42, Dimitri John Ledkov (dimitri.j.ledkov at intel.com) wrote:
>> On 29 May 2015 at 11:25, Lennart Poettering <lennart at poettering.net> wrote:
>> > On Fri, 29.05.15 00:24, Dimitri John Ledkov (dimitri.j.ledkov at intel.com) wrote:
>> >> On 28 May 2015 at 18:08, Lennart Poettering <lennart at poettering.net> wrote:
>> >> > On Thu, 28.05.15 16:42, Dimitri John Ledkov (dimitri.j.ledkov at intel.com) wrote:
>> >> >
>> >> >> It appears in /proc/self/cgroup as `0::/'
>> >> >
>> >> > What precisely does this fix?
>> >> >
>> >> > I mean, we need to do some major rework of things before the unified
>> >> > hierarchy is really supported in systemd, and this one thing won't
>> >> > really get us too much in this regard, does it?
>> >> >
>> >> I'm starting to explore possibilities to start work towards supporting
>> >> unified cgroups hierarchy, or at least be able to boot with it. I'll
>> >> send a larger patch series in one go later than with all the bits that
>> >> offer something more tangible, albeit disabled by default behind
>> >> configure options (like kdbus) given that unified hierarchy is still
>> >> marked experimental in the kernel.
>> > Ah, it's actually my big thing to work on for the next weeks too...
>> My current priority is to port at least enough bits to get usable
>> /sys/fs/cgroup/systemd on top of unified cgroups, with immediate
>> benefit of dropping systemd-cgroups-agent and getting release
>> notifications in containers.
>> Not sure about transition / re-exec plan, at the moment I am assuming
>> either/or situation but I guess we'd need to support a dual case,
>> where upon re-exec we might still be in name=systemd rather than in
>> the unified structure.
> My intention is to make this all work so that we can support both
> modes for a while, but you have to pick at boot-time which mode you
> want: the unified hierarchy or the classic one. And if we pick the
> former you won't get the latter, and if you pick the latter you won't
> get the former.
> And yeah, getting proper notifications especially for the container
> case is the most important thing for me too.
Right. I have it as compile option at the moment, and i'm booting
fresh VMs with it. I do something rather crazy at the moment - mount
/sys/fs/cgroup/systemd as unified hiearchy whilst keeping the old
controller mounts where they are. Will add the bits for the inotify
watches and then publish an RFC patch set. This way systemd gains the
notification benefit straight away, whilst keeping the rest as it was
essentially. I take it the unitfied structure is expected to be
mounted in /sys/fs/cgroup/ direct, once stable.
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