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Message-ID: <45BEA41A.6020209@mbligh.org>
Date: Mon, 29 Jan 2007 17:49:14 -0800
From: "Martin J. Bligh" <mbligh@mbligh.org>
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To: Andrew Morton <akpm@osdl.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>, linux-kernel@vger.kernel.org,
       linux-mm@kvack.org, Ingo Molnar <mingo@elte.hu>
Subject: Re: [PATCH] mm: remove global locks from mm/highmem.c
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Andrew Morton wrote:
> On Mon, 29 Jan 2007 17:31:20 -0800
> "Martin J. Bligh" <mbligh@mbligh.org> wrote:
> 
>> Peter Zijlstra wrote:
>>> On Sun, 2007-01-28 at 14:29 -0800, Andrew Morton wrote:
>>>
>>>> As Christoph says, it's very much preferred that code be migrated over to
>>>> kmap_atomic().  Partly because kmap() is deadlockable in situations where a
>>>> large number of threads are trying to take two kmaps at the same time and
>>>> we run out.  This happened in the past, but incidences have gone away,
>>>> probably because of kmap->kmap_atomic conversions.
>>>> From which callsite have you measured problems?
>>> CONFIG_HIGHPTE code in -rt was horrid. I'll do some measurements on
>>> mainline.
>>>
>> CONFIG_HIGHPTE is always horrid -we've known that for years.
> 
> We have?  What's wrong with it?  <looks around for bug reports>

http://www.ussg.iu.edu/hypermail/linux/kernel/0307.0/0463.html

July 2003.


M.
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