From: Gary Hade <garyhade@us.ibm.com>
To: Dave Hansen <dave@linux.vnet.ibm.com>
Cc: Yasunori Goto <y-goto@jp.fujitsu.com>,
Gary Hade <garyhade@us.ibm.com>,
linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
Badari Pulavarty <pbadari@us.ibm.com>, Mel Gorman <mel@csn.ul.ie>,
Chris McDermott <lcm@us.ibm.com>,
linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
Greg KH <greg@kroah.com>,
Nish Aravamudan <nish.aravamudan@gmail.com>
Subject: Re: [PATCH] mm: show node to memory section relationship with symlinks in sysfs
Date: Tue, 30 Sep 2008 12:41:22 -0700 [thread overview]
Message-ID: <20080930194122.GA7123@us.ibm.com> (raw)
In-Reply-To: <1222789837.17630.41.camel@nimitz>
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.
>
> We'll probably need multiple symlinks in each section directory.
or perhaps symlinks to the same section directory from >1 node directory.
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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next prev parent reply other threads:[~2008-09-30 19:42 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-09-29 20:05 Gary Hade
2008-09-30 8:06 ` Yasunori Goto
2008-09-30 15:50 ` Dave Hansen
2008-09-30 19:41 ` Gary Hade [this message]
2008-10-01 2:48 ` Yasunori Goto
2008-10-01 16:51 ` Gary Hade
2008-09-30 23:29 ` Gary Hade
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