Re: [PATCH 2.5.43-mm2] New shared page table patch

From: Eric W. Biederman (ebiederm@xmission.com)
Date: Mon Oct 21 2002 - 09:55:24 EST


"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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