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Date: Wed, 13 Jan 2010 14:27:07 -0800
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Andi Kleen <andi@firstfloor.org>
CC: Yinghai Lu <yinghai@kernel.org>, Suresh Siddha <suresh.b.siddha@intel.com>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       "ananth@in.ibm.com" <ananth@in.ibm.com>, Ingo Molnar <mingo@elte.hu>,
       Thomas Gleixner <tglx@linutronix.de>,
       Andrew Morton <akpm@linux-foundation.org>,
       "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH -v2 5/5] x86: use dmi check to treat disabled cpus as
 hotplug cpus.
References: <1263338274-6485-1-git-send-email-yinghai@kernel.org> <1263338274-6485-5-git-send-email-yinghai@kernel.org> <1263340563.2854.1011.camel@sbs-t61.sc.intel.com> <4B4D0E39.10200@kernel.org> <87tyupfzk8.fsf@basil.nowhere.org> <4B4E427D.9090207@zytor.com> <20100113222348.GE24818@basil.fritz.box>
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On 01/13/2010 02:23 PM, Andi Kleen wrote:
>> There are configurations in which percpu memory is in the megabytes.
> 
> There used to be some like this (with some broken debug code), but they
> got all fixed i believe to only allocate on real cpu hotplug. 
> 
> If not the right way is to fix them, not add DMI blacklists.
> 
> Beside when you enable debug code you probably don't care about 
> a few MB too much.
> 
>> This is exactly why we need high water mark allocation of percpu memory:
> 
> No we just need to fix any percpu pigs (if there are really any left,
> I did a couple of patches some time ago)
> 
> "Don't work around broken code -- fix it"
> 

Well, that *is* working around broken code, in this case the broken code
is the percpu allocation strategy.

	-hpa