Messages in this thread | | | Date | Tue, 26 Jan 2016 14:51:53 -0800 | From | Andrew Morton <> | Subject | Re: [RFC PATCH] mm: support CONFIG_ZONE_DEVICE + CONFIG_ZONE_DMA |
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On Tue, 26 Jan 2016 14:33:48 -0800 Dan Williams <dan.j.williams@intel.com> wrote:
> >> Towards this end, alias ZONE_DMA and ZONE_DEVICE to work around needing > >> to maintain a unique zone number for ZONE_DEVICE. Record the geometry > >> of ZONE_DMA at init (->init_spanned_pages) and use that information in > >> is_zone_device_page() to differentiate pages allocated via > >> devm_memremap_pages() vs true ZONE_DMA pages. Otherwise, use the > >> simpler definition of is_zone_device_page() when ZONE_DMA is turned off. > >> > >> Note that this also teaches the memory hot remove path that the zone may > >> not have sections for all pfn spans (->zone_dyn_start_pfn). > >> > >> A user visible implication of this change is potentially an unexpectedly > >> high "spanned" value in /proc/zoneinfo for the DMA zone. > > > > Well, all these icky tricks are to avoid increasing ZONES_SHIFT, yes? > > Is it possible to just use ZONES_SHIFT=3? > > Last I tried I hit this warning in mm/memory.c > > #warning Unfortunate NUMA and NUMA Balancing config, growing > page-frame for last_cpupid.
Well yes, it may take a bit of work - perhaps salvaging a bit from somewhere else if poss. But that might provide a better overall solution so could you please have a think?
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