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Date: Thu, 8 Jan 2009 07:52:35 +0100
From: Andi Kleen <andi@firstfloor.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
       Dave Kleikamp <shaggy@linux.vnet.ibm.com>,
       Peter Zijlstra <peterz@infradead.org>, paulmck@linux.vnet.ibm.com,
       Gregory Haskins <ghaskins@novell.com>, Ingo Molnar <mingo@elte.hu>,
       Matthew Wilcox <matthew@wil.cx>, Andi Kleen <andi@firstfloor.org>,
       Chris Mason <chris.mason@oracle.com>,
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       Peter Morreale <pmorreale@novell.com>,
       Sven Dietrich <SDietrich@novell.com>
Subject: Re: [PATCH -v5][RFC]: mutex: implement adaptive spinning
Message-ID: <20090108065235.GX496@one.firstfloor.org>
References: <alpine.LFD.2.00.0901070816450.3057@localhost.localdomain> <1231347442.11687.344.camel@twins> <alpine.LFD.2.00.0901071016340.3057@localhost.localdomain> <alpine.DEB.1.10.0901071530490.23456@gandalf.stny.rr.com> <alpine.LFD.2.00.0901071241360.3057@localhost.localdomain> <1231365115.11687.361.camel@twins> <alpine.LFD.2.00.0901071355350.3057@localhost.localdomain> <1231368870.6686.16.camel@norville.austin.ibm.com> <alpine.LFD.2.00.0901071518570.3057@localhost.localdomain> <alpine.DEB.1.10.0901071848431.23456@gandalf.stny.rr.com>
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> What about memory hotplug as Ingo mentioned?
> 
> Should that be:
> 
> #if defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_MEMORY_HOTPLUG)

We expect memory hotunplug to only really work in movable zones
(all others should at least have one kernel object somewhere that prevents
unplug) and you can't have task structs in movable zones obviously

So it's probably a non issue in practice.

-Andi
-- 
ak@linux.intel.com