[Ksummit-2012-discuss] [ATTEND] General container technology

[Jeff Liu]

On 06/22/2012 03:53 PM, Balbir Singh wrote:

> On Thu, Jun 21, 2012 at 6:44 PM, Jeff Liu <jeff.liu at oracle.com> wrote:
>> Hello,
>>
>> I'd like to seek an opportunity to attend this year's KS, especially interesting to get involved in the general
>> container technology discussion that Glauber has proposed.
>>
>> I am a new comer in kernel upstream, I started playing with kernel after transfer to Oracle kernel team around Sep，2011,
>> and then got started to study the kernel container's technology, as well as maintains the LXC tools on our Enterprise Linux release.
>>
>> Ashamed to say, I have only done some trivial patches in the past 10 months, includes introduce SEEK_DATA/SEEK_HOLE to XFS/EXT4, the former
>> has been merged, but the latter was still pending due to some dependent things, and fix a few bugs for Btrfs/XFS.
>>
>> Recently, I have tried to implement the container disk quota feature, and got some positive feedbacks in V2 patch set.
>> http://comments.gmane.org/gmane.linux.kernel.containers/23242
>> The V3 patch set is still in development stage.
>>
>> Before posting V3 to the list, I'd like to improve the VFS quota scalability firstly. IMHO, the container quota could also get potential
>> performance benefits from that.  Now the idea is to move those global locks as well as the global dquot hash list to individual super block.
>> There is no code change requirement from the file system's(which are bound to VFS quota) perspective except OCFS2, it need a bits fix up accordingly since
>> it use the exported dq_data_lock from dquot.
>>
>> Now the initial patch is basically done, however, I still waiting for a powerful server with multiple cores to
>> measure the lock contentions.
>>
>> Besides above, I'd like to discuss some corner things regarding general containers.
>>
>> * PROC-SYSCTL.
>> There are a couple of proc files are still be global effective IMHO, especially from the LXC guest's point of view, like:
>> /proc/sys/fs/max-nr
>> /proc/sys/fs/nr_open
>> /proc/sys/fs/epoll/max_user_watches
>>
>> /proc/sys/net/core/somaxconn
>> /proc/sys/net/core/netdev_max_backlog
>> /proc/sys/net/core/rmem_default
>> /proc/sys/net/core/rmem_max
>> /proc/sys/net/core/wmem_default
>> /proc/sys/net/core/wmem_max
>>
>> /proc/sys/net/netfilter/nf_conntrack_max
>> /proc/sys/net/netfilter/nf_conntrack_tcp_max_retrans
>> /proc/sys/kernel/threads-max
>>
>> * Fork bomb, make sense?
>>
>> * Network.
>> AFAICS, there is no isolation for iptables and NFS for now.
>> Add a new iptable rule insides the container guest, it will presented on the outsides list, and vice versa.
>>
>> NFS has same issue too, any modification to container guest's /etc/exports could be observed from the outsides, and
>> showmount(8) even does not work, it just hang instead :(  Am not sure supply NFS support at container is reasonable or not.
>>
>> * Testing.
>> Previously, we only run sanity check for container on our Linux release, as the main features are supplied in kernel, we hope to automate
>> those related subsystem tests as as far as possible.  If there already have such tools in the community, I'd like to take part it.
>>
>> * Wiki page for container?
>> Is is make sense to set up a wiki page for container development collaboration?
>> Maybe it would be helpful if we have a wiki page with the features update, new ideas, as well the status of the ongoing tasks.
>>
>>
>> Last but not least, I know it's pretty difficult to get an approval from the KS committees as a junior. What I can do is to continue to make more
>> contributions, and screwed up my courage to send this email out. ^_^
> 
> If there is a container/mm minisummit I'd love to attend. I have not
> kept pace with memcg and cgroups in general, but I'd love to start
> tracking them again

Yeah, glauber's topic is just meet yours. :)
http://lists.linux-foundation.org/pipermail/ksummit-2012-discuss/2012-June/000106.html

I posting those general things as am interesting to work on if possible.


Thanks,
-Jeff