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authorHugh Dickins <hugh@veritas.com>2005-10-29 18:16:40 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2005-10-29 21:40:42 -0700
commit4c21e2f2441dc5fbb957b030333f5a3f2d02dea7 (patch)
tree1f76d33bb1d76221c6424bc5fed080a4f91349a6 /mm/swap_state.c
parentb38c6845b695141259019e2b7c0fe6c32a6e720d (diff)
downloadvexpress-lsk-4c21e2f2441dc5fbb957b030333f5a3f2d02dea7.tar.gz
[PATCH] mm: split page table lock
Christoph Lameter demonstrated very poor scalability on the SGI 512-way, with a many-threaded application which concurrently initializes different parts of a large anonymous area. This patch corrects that, by using a separate spinlock per page table page, to guard the page table entries in that page, instead of using the mm's single page_table_lock. (But even then, page_table_lock is still used to guard page table allocation, and anon_vma allocation.) In this implementation, the spinlock is tucked inside the struct page of the page table page: with a BUILD_BUG_ON in case it overflows - which it would in the case of 32-bit PA-RISC with spinlock debugging enabled. Splitting the lock is not quite for free: another cacheline access. Ideally, I suppose we would use split ptlock only for multi-threaded processes on multi-cpu machines; but deciding that dynamically would have its own costs. So for now enable it by config, at some number of cpus - since the Kconfig language doesn't support inequalities, let preprocessor compare that with NR_CPUS. But I don't think it's worth being user-configurable: for good testing of both split and unsplit configs, split now at 4 cpus, and perhaps change that to 8 later. There is a benefit even for singly threaded processes: kswapd can be attacking one part of the mm while another part is busy faulting. Signed-off-by: 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/swap_state.c')
-rw-r--r--mm/swap_state.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/mm/swap_state.c b/mm/swap_state.c
index 132164f7d0a..cafc1edcbeb 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -83,7 +83,7 @@ static int __add_to_swap_cache(struct page *page, swp_entry_t entry,
page_cache_get(page);
SetPageLocked(page);
SetPageSwapCache(page);
- page->private = entry.val;
+ set_page_private(page, entry.val);
total_swapcache_pages++;
pagecache_acct(1);
}
@@ -126,8 +126,8 @@ void __delete_from_swap_cache(struct page *page)
BUG_ON(PageWriteback(page));
BUG_ON(PagePrivate(page));
- radix_tree_delete(&swapper_space.page_tree, page->private);
- page->private = 0;
+ radix_tree_delete(&swapper_space.page_tree, page_private(page));
+ set_page_private(page, 0);
ClearPageSwapCache(page);
total_swapcache_pages--;
pagecache_acct(-1);
@@ -197,7 +197,7 @@ void delete_from_swap_cache(struct page *page)
{
swp_entry_t entry;
- entry.val = page->private;
+ entry.val = page_private(page);
write_lock_irq(&swapper_space.tree_lock);
__delete_from_swap_cache(page);