[PATCH] More page migration: do not inc/dec rss counters

If we install a migration entry then the rss not really decreases since the
page is just moved somewhere else.  We can save ourselves the work of
decrementing and later incrementing which will just eventually cause cacheline
bouncing.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/mm/migrate.c b/mm/migrate.c
index 8f91463..96b9546 100644 (file)
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -164,7 +164,6 @@ static void remove_migration_pte(struct vm_area_struct *vma, unsigned long addr,
        if (!is_migration_entry(entry) || migration_entry_to_page(entry) != old)
                goto out;
 
-       inc_mm_counter(mm, anon_rss);
        get_page(new);
        pte = pte_mkold(mk_pte(new, vma->vm_page_prot));
        if (is_write_migration_entry(entry))

diff --git a/mm/rmap.c b/mm/rmap.c
index a53a10b..05d6d73 100644 (file)
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -595,6 +595,7 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
                                        list_add(&mm->mmlist, &init_mm.mmlist);
                                spin_unlock(&mmlist_lock);
                        }
+                       dec_mm_counter(mm, anon_rss);
                } else {
                        /*
                         * Store the pfn of the page in a special migration
@@ -606,7 +607,6 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
                }
                set_pte_at(mm, address, pte, swp_entry_to_pte(entry));
                BUG_ON(pte_file(*pte));
-               dec_mm_counter(mm, anon_rss);
        } else
                dec_mm_counter(mm, file_rss);