2009 kernel summit preparation for 'containers end-game' discussion

[Oren Laadan]

Hi,

Serge E. Hallyn wrote:
> Hi,
> 
> the kernel summit is rapidly approaching. One of the agenda
> items is 'the containers end-game and how do we get there.'
> As of now I don't yet know who will be there to represent the
> containers community in that discussion.  I hope there is
> someone planning on that?  In the hopes that there is, here is
> a summary of the info I gathered in June, in case that is
> helpful.  If it doesn't look like anyone will be attending
> ksummit representing containers, then I'll send the final
> version of this info to the ksummit mailing list so that someone
> can stand in.
> 
> 1. There will be an IO controller minisummit before KS.  I
> trust someone (Balbir?) will be sending meeting notes to
> the cgroup list, so that highlights can be mentioned at KS?
> 
> 2. There was a checkpoint/restart BOF plus talk at plumber's.
> Notes on the BOF are here:
> https://lists.linux-foundation.org/pipermail/containers/2009-September/020915.html

Based on Suka's post, I updated the linux-cr wiki page with the
notes from the BOF here:

	http://ckpt.wiki.kernel.org/index.php/LPC2009

> 
> 3. There was an OOM notification talk or BOF at plumber's.
> Dave or Balbir, are there any notes about that meeting?
> 
> 4. The actual title of the KS discussion is 'containers end-game'.
> The containers-specific info I gathered in June was mainly about
> additional resources which we might containerize.  I expect that
> will be useful in helping the KS community decide how far down
> the containerization path they are willing to go - i.e. whether
> we want to call what we have good enough and say you must use kvm
> for anything more, whether we want to be able to provide all the
> features of a full VM with containers, or something in between,
> say targetting specific uses (perhaps only expand on cooperative
> resource management containers).  With that in mind, here are
> some items that were mentioned in June as candidates for
> more containerization work
> 
> 	1. Cpu hard limits, memory soft limits (Balbir)
> 	2. Large pages, mlock, shared page accounting (Balbir)
> 	3. Oom notification (Balbir - was anything decided on this
> 		at plumber's?)
> 	4. There is agreement on getting rid of the ns cgroup,
> 		provided that:
> 		a. user namespaces can provide container confinement
> 		guarantees
> 		b. a compatibility flag is created to clone parent
> 		cgroup when creating a new cgroup (Paul and Daniel)
> 	5. Poweroff/reboot handling in containers (Daniel)
> 	6. Full user namespaces to segragate uids in different
> 		containers and confine root users in containers, i.e.
> 		with respect to file systems like cgroupfs.
> 	7. Checkpoint/restart (c/r) will want time virtualization (Daniel)
> 	8. C/r will want inode virtualization (Daniel)

What is the status on device namespace/virtualization ?  the first few
I have in mind are per-container: /dev/rtc, /dev/ttyX, and even
dev/urandom (isolated entropy pools?).

The first two are important for containers that hold user sessions
(e.g. linux terminal server) - is anyone pushing this use-case in the
context of containers-end-game ?

Oren.

> 	9. Sunrpc containerization (required to allow multiple
> 		containers separate NFS client access to the same server)
> 	10. Sysfs tagging, support for physical netifs to migrate
> 		network namespaces, and /sys/class/net virtualization
> 
> Again the point of this list isn't to ask for discussion about
> whether or how to implement each at this KS, but rather to give
> an idea of how much work is left to do.  Though let the discussion
> lead where it may of course.
> 
> I don't have it here, but maybe it would also be useful to
> have a list ready of things we can do today with containerization?
> Both with upstream, and with under-development patchsets.
> 
> I also hope that someone will take notes on the ksummit
> discussion to send to the containers and cgroup lists.
> I expect there will be a good LWN writeup, but a more
> containers-focused set of notes will probably be useful
> too.
> 
> thanks,
> -serge
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