diff options
author | Nick Piggin <nickpiggin@yahoo.com.au> | 2006-01-06 00:11:12 -0800 |
---|---|---|
committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-01-06 08:33:27 -0800 |
commit | 9617d95e6e9ffd883cf90a89724fe60d7ab22f9a (patch) | |
tree | 67d555d34d931bd253fbc4959ffdb1e5b904f2b0 /mm/rmap.c | |
parent | 224abf92b2f439a9030f21d2926ec8047d1ffcdb (diff) | |
download | kernel_samsung_smdk4412-9617d95e6e9ffd883cf90a89724fe60d7ab22f9a.zip kernel_samsung_smdk4412-9617d95e6e9ffd883cf90a89724fe60d7ab22f9a.tar.gz kernel_samsung_smdk4412-9617d95e6e9ffd883cf90a89724fe60d7ab22f9a.tar.bz2 |
[PATCH] mm: rmap optimisation
Optimise rmap functions by minimising atomic operations when we know there
will be no concurrent modifications.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Hugh Dickins <hugh@veritas.com>
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 | 49 |
1 files changed, 38 insertions, 11 deletions
@@ -435,6 +435,26 @@ int page_referenced(struct page *page, int is_locked) } /** + * page_set_anon_rmap - setup new anonymous rmap + * @page: the page to add the mapping to + * @vma: the vm area in which the mapping is added + * @address: the user virtual address mapped + */ +static void __page_set_anon_rmap(struct page *page, + struct vm_area_struct *vma, unsigned long address) +{ + struct anon_vma *anon_vma = vma->anon_vma; + + BUG_ON(!anon_vma); + anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; + page->mapping = (struct address_space *) anon_vma; + + page->index = linear_page_index(vma, address); + + inc_page_state(nr_mapped); +} + +/** * page_add_anon_rmap - add pte mapping to an anonymous page * @page: the page to add the mapping to * @vma: the vm area in which the mapping is added @@ -445,20 +465,27 @@ int page_referenced(struct page *page, int is_locked) void page_add_anon_rmap(struct page *page, struct vm_area_struct *vma, unsigned long address) { - if (atomic_inc_and_test(&page->_mapcount)) { - struct anon_vma *anon_vma = vma->anon_vma; - - BUG_ON(!anon_vma); - anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; - page->mapping = (struct address_space *) anon_vma; - - page->index = linear_page_index(vma, address); - - inc_page_state(nr_mapped); - } + if (atomic_inc_and_test(&page->_mapcount)) + __page_set_anon_rmap(page, vma, address); /* else checking page index and mapping is racy */ } +/* + * page_add_new_anon_rmap - add pte mapping to a new anonymous page + * @page: the page to add the mapping to + * @vma: the vm area in which the mapping is added + * @address: the user virtual address mapped + * + * Same as page_add_anon_rmap but must only be called on *new* pages. + * This means the inc-and-test can be bypassed. + */ +void page_add_new_anon_rmap(struct page *page, + struct vm_area_struct *vma, unsigned long address) +{ + atomic_set(&page->_mapcount, 0); /* elevate count by 1 (starts at -1) */ + __page_set_anon_rmap(page, vma, address); +} + /** * page_add_file_rmap - add pte mapping to a file page * @page: the page to add the mapping to |