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Date: Sat, 06 Sep 2008 16:06:38 +0900
From: Yasunori Goto <y-goto@jp.fujitsu.com>
To: Andi Kleen <andi@firstfloor.org>
Subject: Re: [PATCH] [RESEND] x86_64: add memory hotremove config option
Cc: 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,
       x86@kernel.org, Ingo Molnar <mingo@elte.hu>
In-Reply-To: <20080906000154.GC18288@one.firstfloor.org>
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> > I am not sure if I understand why you appear to be opposed to
> > enabling the hotremove function before all the issues related
> 
> I'm quite sceptical that it can be ever made to work in a useful
> way for real hardware (as opposed to an hypervisor para virtual setup
> for which this interface is not the right way -- it should be done
> in some specific driver instead) 
> And if it cannot be made to work then it will be a false promise
> to the user. They will see it and think it will work, but it will
> not.
> 
> This means I don't see a real use case for this feature.

I don't think its driver is almighty.
IIRC, balloon driver can be cause of fragmentation for 24-7 system.

In addition, I have heard that memory hotplug would be useful for reducing
of power consumption of DIMM.

I have to admit that memory hotplug has many issues, but I would like to
solve them step by step.


Thanks.
-- 
Yasunori Goto