[Devel] Re: [ckrm-tech] containers development plans (July 10
haveblue at us.ibm.com
Wed Jul 11 11:04:06 PDT 2007
On Wed, 2007-07-11 at 21:18 +0900, Takenori Nagano wrote:
> I think Balbir's idea is very simple and reasonable way to develop per container
> swapping. Because kernel needs the information that a target page belongs to
> which container. Fortunately, we already had page based memory management system
> which included in RSS controller. I think it is appropriate that we develop per
> container swapping on page based memory management system.
There are a couple of concepts being thrown about here, so let's
separate them out a bit.
1. Limit a container's usage of swap.
- Keep track of how many swap pages a container uses
- go OOM on the container when it exceeds its allowed usage
- tracking will be on a container's use of swap globally, no matter
what swap device or file it is actually allocated in
- all containers share all swapfiles
2. Keep separate lists of swap devices for each container
- each container is allowed to use a subset of the system's
- keep a per-container list of which pte values correspond
to which swapfiles
- pte swap values are only valid inside of one container
3. Use a completely isolated set of swapfiles from (2) for
- ensures that any swapfile will only contain data from one container
The idea in (1) is not very useful for checkpoint/restart, but it would
be useful to solve the cpuset OOM problem described in the VM BOF.
( That problem is basically that a cpuset with available memory but a
large amount in swap can cause another cpuset to go OOM. The memory
footprint in the system is under RAM+swap, but the OOM still happens.)
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