Commit 5f527c2b authored May 20, 2016 by Andrea Arcangeli Committed by Linus Torvalds May 20, 2016

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@redhat.com

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 7b8da4c7

include/linux/mm.h

+1 −2

Original line number	Diff line number	Diff line
		@@ -475,8 +475,7 @@ static inline atomic_t compound_mapcount_ptr(struct page page)

		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;
		}