Re: [PATCH] mm: show node to memory section relationship with symlinks in sysfs

Dave Hansen
2008-09-30T15:51:14Z

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.

We'll probably need multiple symlinks in each section directory.

-- Dave