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From: Andrew Morton <akpm@linux-foundation.org>
To: Christoph Lameter <clameter@sgi.com>
Cc: Andi Kleen <ak@suse.de>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	LKML <linux-kernel@vger.kernel.org>, GOTO <y-goto@jp.fujitsu.com>,
	Christoph Lameter <clameter@engr.sgi.com>
Subject: Re: [2.6.20][PATCH] fix mempolicy error check on a system with memory-less-node
Date: Thu, 8 Feb 2007 11:26:29 -0800	[thread overview]
Message-ID: <20070208112629.3a4ce158.akpm@linux-foundation.org> (raw)
In-Reply-To: <Pine.LNX.4.64.0702081106460.11045@schroedinger.engr.sgi.com>

On Thu, 8 Feb 2007 11:09:40 -0800 (PST) Christoph Lameter <clameter@sgi.com> wrote:

> > > > and to 
> > > > accurately present the machine's topology to the user without us having to
> > > > go adding falsehoods like this?
> > > 
> > > a node is a piece of memory. Without memory it doesn't make sense.
> > 
> > Who said?  I can pick up a piece of circuitry which has four CPUs and no
> > RAM, wave it about then stick it in a computer.  The kernel is just wrong,
> > surely?
> 
> Surely your computer has some memory so attach it to that memory (which 
> in a NUMA system would be one or the other node).

"attach it".  But it _isn't_ attached.  There is no memory on this node. 
We seem to be saying that we should misrepresent the physical topology
because the kernel doesn't handle it appropriately.

> Cpu only "nodes" would mean that all memory would be off node. Meaning 
> whatever interconnect one has would be heavily used. Operating system and 
> application performance will suffer.

>From this a logical step would be to change the kernel to refuse to bring
memoryless nodes online at all.

If that's not an approproate solution, then there must be a legtimate
reason for using memoryless nodes.  

Which is it?

  reply	other threads:[~2007-02-08 19:26 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-02-06 11:23 KAMEZAWA Hiroyuki
2007-02-06 17:26 ` Christoph Lameter
2007-02-07  1:14   ` KAMEZAWA Hiroyuki
2007-02-07  8:04     ` Christoph Lameter
2007-02-07  8:36       ` KAMEZAWA Hiroyuki
2007-02-08 11:49         ` Bob Picco
2007-02-07 10:20       ` Andi Kleen
2007-02-07 10:20 ` Andi Kleen
2007-02-07 10:07   ` KAMEZAWA Hiroyuki
2007-02-07 10:19     ` Andi Kleen
2007-02-07 10:37       ` KAMEZAWA Hiroyuki
2007-02-07 10:41         ` Andi Kleen
2007-02-07 10:49           ` KAMEZAWA Hiroyuki
2007-02-07 11:32             ` Andi Kleen
2007-02-07 12:27               ` KAMEZAWA Hiroyuki
2007-02-07 14:05     ` Christoph Lameter
2007-02-07 15:28       ` KAMEZAWA Hiroyuki
2007-02-07 14:03   ` Christoph Lameter
2007-02-07 16:23   ` Andrew Morton
2007-02-07 16:50     ` Andi Kleen
2007-02-07 17:43       ` Andrew Morton
2007-02-07 18:15         ` [PATCH] FS : Speedup rw_verify_area() Eric Dumazet
2007-02-08  0:37         ` [2.6.20][PATCH] fix mempolicy error check on a system with memory-less-node KAMEZAWA Hiroyuki
2007-02-08 19:09         ` Christoph Lameter
2007-02-08 19:26           ` Andrew Morton [this message]
2007-02-08 19:35             ` Christoph Lameter

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