Messages in this thread | | | Date | Fri, 02 Mar 2007 07:09:31 +0530 | From | Balbir Singh <> | Subject | Re: The performance and behaviour of the anti-fragmentation related patches |
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Andrew Morton wrote: > So some urgent questions are: how are we going to do mem hotunplug and > per-container RSS? > > > > Our basic unit of memory management is the zone. Right now, a zone maps > onto some hardware-imposed thing. But the zone-based MM works *well*. I > suspect that a good way to solve both per-container RSS and mem hotunplug > is to split the zone concept away from its hardware limitations: create a > "software zone" and a "hardware zone". All the existing page allocator and > reclaim code remains basically unchanged, and it operates on "software > zones". Each software zones always lies within a single hardware zone. > The software zones are resizeable. For per-container RSS we give each > container one (or perhaps multiple) resizeable software zones. > > For memory hotunplug, some of the hardware zone's software zones are marked > reclaimable and some are not; DIMMs which are wholly within reclaimable > zones can be depopulated and powered off or removed. > > NUMA and cpusets screwed up: they've gone and used nodes as their basic > unit of memory management whereas they should have used zones. This will > need to be untangled. > > > Anyway, that's just a shot in the dark. Could be that we implement unplug > and RSS control by totally different means. But I do wish that we'd sort > out what those means will be before we potentially complicate the story a > lot by adding antifragmentation. >
Paul Menage had suggested something very similar in response to the RFC for memory controllers I sent out and it was suggested that we create small zones (roughly 64 MB) to avoid the issue of a zone/node not being a shareable across containers. Even with a small size, there are some issues. The following thread has the details discussed.
http://lkml.org/lkml/2006/10/30/120
RSS accounting is very easy (with minimal changes to the core mm), supplemented with an efficient per-container reclaimer, it should be easy to implement a good per-container RSS controller.
-- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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