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Date: Wed, 16 Jul 2003 16:25:32 +0100
From: Dave Jones <davej@codemonkey.org.uk>
To: Hugh Dickins <hugh@veritas.com>
Cc: Ron Niles <Ron.Niles@falconstor.com>, linux-kernel@vger.kernel.org
Subject: Re: Question about free_one_pgd() changes in these 3.5G patches
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	Hugh Dickins <hugh@veritas.com>,
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On Wed, Jul 16, 2003 at 01:31:39PM +0100, Hugh Dickins wrote:

Both this..

 > > 	for (j = 0; j < PTRS_PER_PMD ; j++) {
 > >  		prefetchw(pmd+j+(PREFETCH_STRIDE/16));
 > > 		free_one_pmd(pmd+j);
 > > 	}

and this..

 > > 	pmd_t * pmd, * md, * emd;
 > > 	for (md = pmd, emd = pmd + PTRS_PER_PMD; md < emd; md++) {
 > > 		prefetchw(md+(PREFETCH_STRIDE/16));
 > > 		free_one_pmd(md);
 > >  	}

both use the prefetch that was removed in 2.5 for 'being bogus'.
It can prefetch past the end iirc, which is fatal on some CPUs.

		Dave