Re: [PATCH] POWER 4 fails to boot with NUMA

["Martin J. Bligh" <mbligh@mbligh.org>]

--Sonny Rao <sonny@burdell.org> wrote (on Monday, August 01, 2005 02:23:22 -0400):

> On Mon, Aug 01, 2005 at 12:27:42AM -0500, Paul Mackerras wrote:
>> From: Mike Kravetz <kravetz@us.ibm.com>
>> 
>> If CONFIG_NUMA is set, some POWER 4 systems will fail to boot.  This is
>> because of special processing needed to handle invalid node IDs (0xffff)
>> on POWER 4.  My previous patch to handle memory 'holes' within nodes
>> forgot to add this special case for POWER 4 in one place.
>> 
>> In reality, I'm not sure that configuring the kernel for NUMA on POWER 4
>> makes much sense.  Are there POWER 4 based systems with NUMA characteristics
>> that are presented by the firmware?  But, distros want one kernel for all
>> systems so NUMA is on by default in their kernels.  The patch handles those
>> cases.
> 
> IIRC, In SMP mode the NUMA topology is exported.  I've tried this on a
> p690 and it worked correctly on older kernels (2.6.10 or 2.6.11) 
> 
> I also noticed a nice speedup on a few things compared to LPAR mode :-)

Yeah, I have a p650 that's set up similarly .... I thought the auto-test
stuff was covering that, but it seems NUMA is not turned on for that box
like I thought it was. will fix ....

M.

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