Re: Question about free_one_pgd() changes in these 3.5G patches

From: Dave Jones (davej@codemonkey.org.uk)
Date: Wed Jul 16 2003 - 10:25:32 EST

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

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