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To: "Martin J. Bligh" <mbligh@aracnet.com>
Cc: Bill Davidsen <davidsen@tmr.com>, Dave McCracken <dmccr@us.ibm.com>,
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Subject: Re: [PATCH 2.5.43-mm2] New shared page table patch
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	<2458064740.1035069495@[10.10.2.3]>
From: ebiederm@xmission.com (Eric W. Biederman)
Date: 21 Oct 2002 08:55:24 -0600
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"Martin J. Bligh" <mbligh@aracnet.com> writes:

> >> For reference, one of the tests was TPC-H.  My code reduced the number of
> >> allocated pte_chains from 5 million to 50 thousand.
> > 
> > Don't tease, what did that do for performance? I see that someone has
> > already posted a possible problem, and the code would pass for complex for
> > most people, so is the gain worth the pain?
> 
> In many cases, this will stop the box from falling over flat on it's 
> face due to ZONE_NORMAL exhaustion (from pte-chains), or even total
> RAM exhaustion (from PTEs). Thus the performance gain is infinite ;-)

So why has no one written a pte_chain reaper?  It is perfectly sane
to allocate a swap entry and move an entire pte_chain to the swap
cache.  

Eric
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