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Date: Wed, 21 Feb 2007 15:27:21 -0800
From: Jeremy Fitzhardinge <jeremy@goop.org>
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To: Rusty Russell <rusty@rustcorp.com.au>
CC: Andi Kleen <ak@suse.de>, Chris Wright <chrisw@sous-sol.org>,
       virtualization@lists.osdl.org,
       Andrew Morton <akpm@linux-foundation.org>,
       xen-devel@lists.xensource.com, linux-kernel@vger.kernel.org
Subject: Re: [Xen-devel] Re: [patch 05/24] Xen-paravirt_ops: Add pagetable
 accessors to pack and unpack pagetable entries
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Rusty Russell wrote:
> On Wed, 2007-02-21 at 23:15 +0100, Andi Kleen wrote:
>   
>> On Wednesday 21 February 2007 21:52, Jeremy Fitzhardinge wrote:
>>     
>>> Add a set of accessors to pack, unpack and modify page table entries
>>> (at all levels).  This allows a paravirt implementation to control the
>>> contents of pgd/pmd/pte entries.  For example, Xen uses this to
>>> convert the (pseudo-)physical address into a machine address when
>>> populating a pagetable entry, and converting back to pphys address
>>> when an entry is read.
>>>       
>> Do you have some lmbench numbers before/after this change? 
>> iirc at least fork and exit do a lot of pte accesses in various forms.
>> If it's measurable it might be needed to patch those for the native case.
>>     
>
> Yes, __mkpte must be patched to avoid performance embarrassment.
>
> Jeremy, did you want me to do this, or are you happy to?
>   
I'm working on it now.  I'll mail out a proposal in a little bit.

    J