The patch titled
Subject: mm: thp: microoptimize compound_mapcount()
has been added to the -mm tree. Its filename is
mm-thp-microoptimize-compound_mapcount.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-thp-microoptimize-compound_mapcount.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-thp-microoptimize-compound_mapcount.patch
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------------------------------------------------------
From: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Subject: mm: thp: microoptimize compound_mapcount()
compound_mapcount() is only called after PageCompound() has already been
checked by the caller, so there's no point to check it again. Gcc may
optimize it away too because it's inline but this will remove the runtime
check for sure and add it'll add an assert instead.
Link: http://lkml.kernel.org/r/1462547040-1737-3-git-send-email-aarcange@xxxxxxxxxx
Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Alex Williamson <alex.williamson@xxxxxxxxxx>
Cc: "Kirill A. Shutemov" <kirill@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mm.h | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff -puN include/linux/mm.h~mm-thp-microoptimize-compound_mapcount include/linux/mm.h
--- a/include/linux/mm.h~mm-thp-microoptimize-compound_mapcount
+++ a/include/linux/mm.h
@@ -471,8 +471,7 @@ static inline atomic_t *compound_mapcoun
static inline int compound_mapcount(struct page *page)
{
- if (!PageCompound(page))
- return 0;
+ VM_BUG_ON_PAGE(!PageCompound(page), page);
page = compound_head(page);
return atomic_read(compound_mapcount_ptr(page)) + 1;
}
_
Patches currently in -mm which might be from aarcange@xxxxxxxxxx are
mm-thp-calculate-the-mapcount-correctly-for-thp-pages-during-wp-faults.patch
mm-thp-microoptimize-compound_mapcount.patch
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