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authorRik van Riel <riel@redhat.com>2010-04-14 17:59:28 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2010-04-19 16:28:20 -0700
commite8a03feb54ca7f1768bbdc2b491f9ef654e6d01d (patch)
tree1ce113d18057e0870e0816f272e21b6716ef321f
parent9b030e2006546366c832911ca5eb9e785408795b (diff)
rmap: add exclusively owned pages to the newest anon_vma
The recent anon_vma fixes cause many anonymous pages to end up in the parent process anon_vma, even when the page is exclusively owned by the current process. Adding exclusively owned anonymous pages to the top anon_vma reduces rmap scanning overhead, especially in workloads with forking servers. This patch adds a parameter to __page_set_anon_rmap that can be used to indicate whether or not the added page is exclusively owned by the current process. Pages added through page_add_new_anon_rmap are exclusively owned by the current process, and can be added to the top anon_vma. Pages added through page_add_anon_rmap can be either shared or exclusively owned, so we do the conservative thing and add it to the oldest anon_vma. A next step would be to add the exclusive parameter to page_add_anon_rmap, to be used from functions where we do know for sure whether a page is exclusively owned. Signed-off-by: Rik van Riel <riel@redhat.com> Reviewed-by: Johannes Weiner <hannes@cmpxchg.org> Lightly-tested-by: Borislav Petkov <bp@alien8.de> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> [ Edited to look nicer - Linus ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/rmap.c27
1 files changed, 16 insertions, 11 deletions
diff --git a/mm/rmap.c b/mm/rmap.c
index 4bad3267537a..526704e8215d 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -730,23 +730,28 @@ void page_move_anon_rmap(struct page *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
+ * @exclusive: the page is exclusively owned by the current process
*/
static void __page_set_anon_rmap(struct page *page,
- struct vm_area_struct *vma, unsigned long address)
+ struct vm_area_struct *vma, unsigned long address, int exclusive)
{
- struct anon_vma_chain *avc;
- struct anon_vma *anon_vma;
+ struct anon_vma *anon_vma = vma->anon_vma;
- BUG_ON(!vma->anon_vma);
+ BUG_ON(!anon_vma);
/*
- * We must use the _oldest_ possible anon_vma for the page mapping!
+ * If the page isn't exclusively mapped into this vma,
+ * we must use the _oldest_ possible anon_vma for the
+ * page mapping!
*
- * So take the last AVC chain entry in the vma, which is the deepest
- * ancestor, and use the anon_vma from that.
+ * So take the last AVC chain entry in the vma, which is
+ * the deepest ancestor, and use the anon_vma from that.
*/
- avc = list_entry(vma->anon_vma_chain.prev, struct anon_vma_chain, same_vma);
- anon_vma = avc->anon_vma;
+ if (!exclusive) {
+ struct anon_vma_chain *avc;
+ avc = list_entry(vma->anon_vma_chain.prev, struct anon_vma_chain, same_vma);
+ anon_vma = avc->anon_vma;
+ }
anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
page->mapping = (struct address_space *) anon_vma;
@@ -802,7 +807,7 @@ void page_add_anon_rmap(struct page *page,
VM_BUG_ON(!PageLocked(page));
VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end);
if (first)
- __page_set_anon_rmap(page, vma, address);
+ __page_set_anon_rmap(page, vma, address, 0);
else
__page_check_anon_rmap(page, vma, address);
}
@@ -824,7 +829,7 @@ void page_add_new_anon_rmap(struct page *page,
SetPageSwapBacked(page);
atomic_set(&page->_mapcount, 0); /* increment count (starts at -1) */
__inc_zone_page_state(page, NR_ANON_PAGES);
- __page_set_anon_rmap(page, vma, address);
+ __page_set_anon_rmap(page, vma, address, 1);
if (page_evictable(page, vma))
lru_cache_add_lru(page, LRU_ACTIVE_ANON);
else