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From: "Martin J. Bligh" <mbligh@mbligh.org>
To: Andi Kleen <ak@suse.de>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@osdl.org>,
	Christoph Lameter <clameter@sgi.com>,
	bob.picco@hp.com
Subject: Re: [RFC] [PATCH] more support for memory-less-node.
Date: Tue, 13 Feb 2007 10:26:32 -0800	[thread overview]
Message-ID: <45D202D8.9080503@mbligh.org> (raw)
In-Reply-To: <200702131918.45885.ak@suse.de>

Andi Kleen wrote:
>> I wasn't suggesting having NULL pointers for pgdats, if that's what you
>> mean. 
> 
> That is what started the original thread at least. Can happen on some
> ia64 platforms.

OK, that does seem kind of ugly.

>> Just nodes with no memory in them, the pgdat would still be there. 
>> pgdat = struct node, except everything's badly named.
> 
> Ok those can happen even on x86-64, mostly because it's possible
> to fill up a node early during boot up with bootmem and then
> it's effectively empty.
> 
> [there is even still a open bug when this happens on node 0]
>  
> Handling out of memory here of course has to be always done.

Yup, if we just set the "size" of the node to zero, it seems
like a natural degenerate case that should be handled anyway.

> Just NULL pointers in core data structures are evil. But I'm glad we 
> agree here.
> 
> Now if it's better to set up a empty node or use a nearby node
> for a memory less cpu can be further discussed. I still think
> I lean towards the later.

Just seems kind of ugly and unnecessary, particularly if that
memory-less cpu (or IO node) is equidistant from one or more
memory-possessing nodes. As long as their zonelist is set up
correctly, it should all work fine without that, right?

build_zonelists_node already checks populated_zone() so it looks
like it's all set up for that already ...

M.


  reply	other threads:[~2007-02-13 18:28 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-02-13  6:57 KAMEZAWA Hiroyuki
2007-02-13  8:29 ` Andi Kleen
2007-02-13  8:38   ` KAMEZAWA Hiroyuki
2007-02-13 17:25     ` Christoph Lameter
2007-02-14  0:12       ` KAMEZAWA Hiroyuki
2007-02-13 17:24   ` Christoph Lameter
2007-02-13 17:09 ` Martin J. Bligh
2007-02-13 17:45   ` Andi Kleen
2007-02-13 18:03     ` Christoph Lameter
2007-02-13 18:16       ` Martin J. Bligh
2007-02-13 18:50         ` Christoph Lameter
2007-02-14  0:20           ` KAMEZAWA Hiroyuki
2007-02-13 18:11     ` Martin J. Bligh
2007-02-13 18:18       ` Andi Kleen
2007-02-13 18:26         ` Martin J. Bligh [this message]
2007-02-13 18:51         ` Bob Picco
     [not found] <7NZO0-6et-1@gated-at.bofh.it>
     [not found] ` <7Oa6N-5If-3@gated-at.bofh.it>
     [not found]   ` <7Oaq4-6ow-7@gated-at.bofh.it>
     [not found]     ` <7Oaq6-6ow-17@gated-at.bofh.it>
2007-02-15 12:21       ` Bodo Eggert

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