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Subject: Re: x86 Page Sizes
From: Steven Cole <elenstev@mesatop.com>
To: Peter Svensson <petersv@psv.nu>
Cc: Robert Love <rml@tech9.net>, Dan Sturtevant <dsturtev@plogic.com>,
       linux-kernel@vger.kernel.org
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Date: 27 Jun 2002 08:26:07 -0600
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On Thu, 2002-06-27 at 00:35, Peter Svensson wrote:
> On 26 Jun 2002, Robert Love wrote:
> 
> > Kernel has 4K pages in user and kernel space.  It is the same address
> > space and segment, just uses MMU protection.
> > 
> > x86 does 4K pages.
> 
> The x86 cpus can use 4K or 4M pages in the hardware. The 4M pages are 
> restricted to the kernel in Linux due to various problems. This has been 
> discussed on this list a while ago. The thread was called "Have the 2.4 
> kernel memory management problems on large machines been fixed?" the last 
> time around.
> 
> 4M pages are useful to minimize tlb misses which can be costly for some 
> algorithms.
> 
> Peter

In addition to that thread, you might want to read the paper "Multiple
Page Size Support in the Linux Kernel", pages 573-593 in the Proceedings
of the Ottawa Linux Symposium which you can download from here:

http://www.linuxsymposium.org/2002/ 

If you're on a slow connection, be forewarned that it is a 631 page pdf,
but thankfully it's compressed.

Steven


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