Messages in this thread | | | Date | Fri, 4 Mar 2011 17:24:30 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | Re: cgroup memory, blkio and the lovely swapping |
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On Fri, 4 Mar 2011 09:11:32 +0100 Daniel Poelzleithner <poelzi@poelzi.org> wrote:
> On Fri, 4 Mar 2011 16:54:55 +0900 > KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote: > > > Now, blkio cgroup does work only with synchronous I/O(direct I/O) > > and never work with swap I/O. And I don't think swap-i/o limit > > is a blkio matter. > > I'm totally unsure about what subsystem it really belongs to. It is > memory for sure, but disk access, which it actually affects, belongs to > the blkio subsystem. Is there a technical reason why swap I/O is not run > through the blkio system ? >
Now, blkio cgroup has no tags on each page. Then, it works only when it can detect a thread which starts I/O in block layer. But there is an activity to fix that.
http://marc.info/?l=linux-mm&m=129888823027871&w=2
I think you can discuss swap io handling in this thread.
> > > Memory cgroup is now developping dirty_ratio for memory cgroup. > > By that, you can control the number of pages in writeback, in memory > > cgroup. I think it will work for you. > > I'm not sure that fixes the fairness problem on swapio. Just having a > larger buffer before a writeback happens will reduce seeks, but not > give fair share of io in swap in. It's good to control over it on > cgroup level, but i doubt it will fix the problem. >
swap-in is out-of-control from memcg's view and have no plans. IHMO, the number of swap-in will be blkio cgroup matter.
Thanks, -Kame
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