tree 07d47e6ff1ab30309004e2ba0674dcabd83945c1
parent d85f33855c303acfa87fa457157cef755b6087df
author Christoph Lameter <clameter@sgi.com> 1178488180 -0700
committer Linus Torvalds <torvalds@woody.linux-foundation.org> 1178565173 -0700

mm: optimize compound_head() by avoiding a shared page flag

The patch adds PageTail(page) and PageHead(page) to check if a page is the
head or the tail of a compound page.  This is done by masking the two bits
describing the state of a compound page and then comparing them.  So one
comparision and a branch instead of two bit checks and two branches.

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>