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| author | Nick Piggin <nickpiggin@yahoo.com.au> | 2005-09-04 00:54:47 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@evo.osdl.org> | 2005-09-05 09:05:43 +0200 |
| commit | 2822c1aa574d277b9ba0130b1e71c1a5874bc04a (patch) | |
| tree | 6a48d5db83831b6521bbc5795a70ea5ab7446b0e /mm/rmap.c | |
| parent | [PATCH] mm: comment rmap (diff) | |
| download | linux-2822c1aa574d277b9ba0130b1e71c1a5874bc04a.tar.xz linux-2822c1aa574d277b9ba0130b1e71c1a5874bc04a.zip | |
[PATCH] mm: micro-optimise rmap
Microoptimise page_add_anon_rmap. Although these expressions are used only in
the taken branch of the if() statement, the compiler can't reorder them inside
because atomic_inc_and_test is a barrier.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'mm/rmap.c')
| -rw-r--r-- | mm/rmap.c | 21 |
1 files changed, 11 insertions, 10 deletions
diff --git a/mm/rmap.c b/mm/rmap.c index f5a6966b7eb0..7e975ca24c78 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -439,22 +439,23 @@ int page_referenced(struct page *page, int is_locked, int ignore_token) void page_add_anon_rmap(struct page *page, struct vm_area_struct *vma, unsigned long address) { - struct anon_vma *anon_vma = vma->anon_vma; - pgoff_t index; - BUG_ON(PageReserved(page)); - BUG_ON(!anon_vma); inc_mm_counter(vma->vm_mm, anon_rss); - anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; - index = (address - vma->vm_start) >> PAGE_SHIFT; - index += vma->vm_pgoff; - index >>= PAGE_CACHE_SHIFT - PAGE_SHIFT; - if (atomic_inc_and_test(&page->_mapcount)) { - page->index = index; + struct anon_vma *anon_vma = vma->anon_vma; + pgoff_t index; + + BUG_ON(!anon_vma); + anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; page->mapping = (struct address_space *) anon_vma; + + index = (address - vma->vm_start) >> PAGE_SHIFT; + index += vma->vm_pgoff; + index >>= PAGE_CACHE_SHIFT - PAGE_SHIFT; + page->index = index; + inc_page_state(nr_mapped); } /* else checking page index and mapping is racy */ |