Messages in this thread | | | Date | Tue, 17 Apr 2012 08:13:52 -0700 | From | Tejun Heo <> | Subject | Re: Cgroup in a single hierarchy (Was: Re: [RFD] Merge task counter into memcg) |
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Hello, Glauber.
On Thu, Apr 12, 2012 at 02:04:24PM -0300, Glauber Costa wrote: > 1) Right now, the controllers work independently, and that code will > have to live for at least some years anyway. So leave it there. > > 2) But also, insert optimization code that can be enabled/disabled > when companion cgroups are in the same hierarchy. > > 3) After we mount the cgroup, apply those optimization to all of > them from the cgroup core (the current bind stuff is just way to > weird for that, IMHO) > > 4) Then we start telling userspace people to favor co-mounts as much > as they can > > 5) Pray.
Pretty similar to the plan that I was thinking about.
* Provide both mechanisms from the kernel while implementing new features / optimizations with the assumption that there's one hierarchy.
* Make the switch to single hierarchy from userland, probably by implementing a (policy based) userland thing which takes over the whole cgroup hierarchy.
* Phase out multiple hierarchy support from kernel slowly.
That said, there are quite a few obstacles including being able to support most (probably not all) use cases possible under multiple hierarchies and managing the added complexity over the transition period. I don't think it's gonna be easy. Needs more thinking.
Thanks.
-- tejun
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