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Date: Sat, 10 Aug 2002 16:55:45 -0300 (BRT)
From: Rik van Riel <riel@conectiva.com.br>
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To: "Eric W. Biederman" <ebiederm@xmission.com>
cc: Andrew Morton <akpm@zip.com.au>, Linus Torvalds <torvalds@transmeta.com>,
       Daniel Phillips <phillips@arcor.de>, <frankeh@watson.ibm.com>,
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       <Martin.Bligh@us.ibm.com>, William Lee Irwin III <wli@holomorphy.com>,
       <linux-kernel@vger.kernel.org>
Subject: Re: large page patch (fwd) (fwd)
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On 10 Aug 2002, Eric W. Biederman wrote:
> Andrew Morton <akpm@zip.com.au> writes:
> >
> > The other worry is the ZONE_NORMAL space consumption of pte_chains.
> > We've halved that, but it will still make high sharing levels
> > unfeasible on the big ia32 machines.

> There is a second method to address this.  Pages can be swapped out
> of the page tables and still remain in the page cache, the virtual
> scan does this all of the time.  This should allow for arbitrary
> amounts of sharing.  There is some overhead, in faulting the pages
> back in but it is much better than cases that do not work.  A simple
> implementation would have a maximum pte_chain length.

Indeed.  We need this same thing for page tables too, otherwise
a high sharing situation can easily "require" more page table
memory than the total amount of physical memory in the system ;)

regards,

Rik
-- 
Bravely reimplemented by the knights who say "NIH".

http://www.surriel.com/		http://distro.conectiva.com/

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