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Message-ID: <4421EB3B.90804@yahoo.com.au>
Date: Thu, 23 Mar 2006 11:26:35 +1100
From: Nick Piggin <nickpiggin@yahoo.com.au>
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To: Keir Fraser <Keir.Fraser@cl.cam.ac.uk>
CC: virtualization@lists.osdl.org, Ian Pratt <ian.pratt@xensource.com>,
       xen-devel@lists.xensource.com, linux-kernel@vger.kernel.org,
       Chris Wright <chrisw@sous-sol.org>
Subject: Re: [RFC PATCH 30/35] Add generic_page_range() function
References: <20060322063040.960068000@sorel.sous-sol.org> <20060322063805.741915000@sorel.sous-sol.org> <44213333.6030404@yahoo.com.au> <79fcd3fd1d13741c5d1cd3c6f5b326b9@cl.cam.ac.uk>
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Keir Fraser wrote:

>> lastly, you don't allow any control over the type of pages that are
>> walked: this could well be unusably slow for some cases. At least
>> you should proably design the interface so we can iterate over
>> present, not present, all, etc so it becomes widely usable. Normally
>> I'd say to wait until users come up but in this case the function
>> isn't a speed demon anyway, and you also don't want to give people
>> any excuses not to use it.
> 
> 
> You mean iterate only over PTEs that are already present, or only those 
> that were *not* previously present, or all (present and non-present)? Is 
> that really useful? If so then yes, it's not hard to add.
> 

Yes. If you look at all the code that walks pagetables (including those
that just operate on a single pte) in arch/ and other places, there is
a fair diversity. A function called generic_page_range() would surely be
able to replace all those ;)

-- 
SUSE Labs, Novell Inc.
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