Messages in this thread | | | Date | Wed, 1 Oct 2008 09:51:05 -0700 | From | Gary Hade <> | Subject | Re: [PATCH] mm: show node to memory section relationship with symlinks in sysfs |
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On Wed, Oct 01, 2008 at 11:48:29AM +0900, Yasunori Goto wrote: > > On Tue, Sep 30, 2008 at 08:50:37AM -0700, Dave Hansen wrote: > > > On Tue, 2008-09-30 at 17:06 +0900, Yasunori Goto wrote: > > > > > +#define section_nr_to_nid(section_nr) pfn_to_nid(section_nr_to_pfn(section_nr)) > > > > > #endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */ > > > > > > > > If the first page of the section is not valid, then this section_nr_to_nid() > > > > doesn't return correct value. > > > > > > > > I tested this patch. In my box, the start_pfn of node 1 is 1200400, but > > > > section_nr_to_pfn(mem_blk->phys_index) returns 1200000. As a result, > > > > the section is linked to node 0. > > > > > > Crap, I was worried about that. > > > > > > Gary, this means that we have a N:1 relationship between NUMA nodes and > > > sections. This normally isn't a problem because sections don't really > > > care about nodes and they layer underneath them. > > > > So, using Yasunori-san's example the memory section starting at > > pfn 1200000 actually resides on both node 0 and node 1. > > > It may be possible that one section is divided to different node in theory. > (I don't know really there is...) > > But, the cause of my trouble differs from it. > There is a memory hole which is occupied by firmware. > So, the memory map of my box is here. > > ---- > early_node_map[3] active PFN ranges > 0: 0x00000100 -> 0x00006d00 > 0: 0x00408000 -> 0x00410000 > 1: 0x01200400 -> 0x01210000 > ---- > > memmap_init() initializes from start_pfn (to end_pfn). > So, the memmaps for this first hole (0x1200000 - 0x12003ff) are not initialized, > and node id is not set for them. This is true cause.
Thanks for the clarification. I think we need to cover both the theoretical single memory section spanning multiple nodes case and your memory hole/memory section intersection case.
Gary
-- Gary Hade System x Enablement IBM Linux Technology Center 503-578-4503 IBM T/L: 775-4503 garyhade@us.ibm.com http://www.ibm.com/linux/ltc
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