On Mon, 4 Dec 2006, Mel Gorman wrote: > 4. Offlining a DIMM > 5. Offlining a Node > > For Situation 4, a zone may be needed because MAX_ORDER_NR_PAGES would have > to be set to too high for anti-frag to be effective. However, zones would > have to be tuned at boot-time and that would be an annoying restriction. If > DIMMs are being offlined for power reasons, it would be sufficient to be > best-effort.
We are able to depopularize a portion of the pages in a MAX_ORDER chunk if the page structs pages on the borders of that portion are not stored on the DIMM. Set a flag in the page struct of those page struct pages straddling the border and free the page struct pages describing only memory in the DIMM. > Situation 5 requires that a hotpluggable node only allows __GFP_MOVABLE > allocations in the zonelists. This would probably involving having one > zone that only allowed __GFP_MOVABLE. This is *node* hotplug and we already have a node/zone structure etc where we could set some option to require only movable allocations. Note that NUMA nodes have always had only a single effective zone. There are some exceptions on some architectures where we have additional DMA zones on the first or first two nodes but NUMA memory policies will *not* allow to exercise control over allocations from those zones. > In other words, to properly address all situations, we may need anti-frag > and zones, not one or the other. I still do not see a need for additional zones. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
