Date: Thu, 12 Jun 2008 05:18:09 +0000 (UTC) From: Alan Cox <alc@FreeBSD.org> To: src-committers@FreeBSD.org, cvs-src@FreeBSD.org, cvs-all@FreeBSD.org Subject: cvs commit: src/sys/amd64/amd64 pmap.c Message-ID: <200806120518.m5C5IJcb067691@repoman.freebsd.org>
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alc 2008-06-12 05:18:09 UTC
FreeBSD src repository
Modified files:
sys/amd64/amd64 pmap.c
Log:
SVN rev 179749 on 2008-06-12 05:18:09Z by alc
Reverse the direction of pmap_promote_pde()'s traversal over the specified
page table page. The direction of the traversal can matter if
pmap_promote_pde() has to remove write access (PG_RW) from a PTE that hasn't
been modified (PG_M). In general, if there are two or more such PTEs to
choose among, it is better to write protect the one nearer the high end of
the page table page rather than the low end. This is because most programs
access memory in an ascending direction. The net result of this change is a
sometimes significant reduction in the number of failed promotion attempts
and the number of pages that are write protected by pmap_promote_pde().
Revision Changes Path
1.620 +28 -12 src/sys/amd64/amd64/pmap.c
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