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From: David Mosberger <davidm@napali.hpl.hp.com>
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Date: Sat, 3 Aug 2002 14:26:27 -0700
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       Gerrit Huizenga <gh@us.ibm.com>, <Martin.Bligh@us.ibm.com>,
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Subject: Re: large page patch (fwd) (fwd)
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>>>>> On Sat, 3 Aug 2002 16:53:39 -0400, Hubertus Franke <frankeh@watson.ibm.com> said:

  Hubertus> Cool.  Does that mean that BSD already has page coloring
  Hubertus> implemented ?

FreeBSD (at least on Alpha) makes some attempts at page-coloring, but
it's said to be far from perfect.

  Hubertus> The agony is: Page Coloring helps to reduce cache
  Hubertus> conflicts in low associative caches while large pages may
  Hubertus> reduce TLB overhead.

Why agony?  The latter helps the TLB _and_ solves the page coloring
problem (assuming the largest page size is bigger than the largest
cache; yeah, I see that could be a problem on some Power 4
machines... ;-)

  Hubertus> One shouldn't rule out one for the other, there is a place
  Hubertus> for both.

  Hubertus> How did you arrive to the (weak) empirical evidence?  You
  Hubertus> checked TLB misses and cache misses and turned page
  Hubertus> coloring on and off and large pages on and off?

Yes, that's basically what we did (there is a patch implementing a
page coloring kernel module floating around).

	--david
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