Hello, On Tue, Jan 26, 2016 at 03:11:36PM -0800, Dan Williams wrote: > On Tue, Jan 26, 2016 at 2:51 PM, Andrew Morton > <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > > On Tue, 26 Jan 2016 14:33:48 -0800 Dan Williams <dan.j.williams@xxxxxxxxx> 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? > > > > Will do, especially since other efforts are feeling the pinch on the > MAX_NR_ZONES limitation. Please refer my previous attempt to add a new zone, ZONE_CMA. https://lkml.org/lkml/2015/2/12/84 It salvages a bit from SECTION_WIDTH by increasing section size. Similarly, I guess we can reduce NODE_WIDTH if needed although it could cause to reduce maximum node size. Thanks. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>