| commit | 6d7779538f765963ced45a3fa4bed7ba8d2c277d | |
| author | Christoph Lameter <clameter@sgi.com> | |
| Sun, 6 May 2007 21:49:40 +0000 (6 14:49 -0700) | ||
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | |
| Mon, 7 May 2007 19:12:53 +0000 (7 12:12 -0700) | ||
| tree | 07d47e6ff1ab30309004e2ba0674dcabd83945c1 | treesnapshot (tar.gz zip) |
| parent | d85f33855c303acfa87fa457157cef755b6087df | commitdiff |
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>
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>
| include/linux/mm.h | diffblobblamehistory | |
| include/linux/page-flags.h | diffblobblamehistory | |
| mm/page_alloc.c | diffblobblamehistory |