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authorHugh Dickins <hugh@veritas.com>2005-09-03 18:54:41 -0400
committerLinus Torvalds <torvalds@evo.osdl.org>2005-09-05 03:05:42 -0400
commit5d337b9194b1ce3b6fd5f3cb2799455ed2f9a3d1 (patch)
tree91ed9ef6f4cb5f6a1832f2baaaabd53fcd83513e /include/linux/swap.h
parent048c27fd72816b44e096997d1c6901c3abbfd45b (diff)
[PATCH] swap: swap_lock replace list+device
The idea of a swap_device_lock per device, and a swap_list_lock over them all, is appealing; but in practice almost every holder of swap_device_lock must already hold swap_list_lock, which defeats the purpose of the split. The only exceptions have been swap_duplicate, valid_swaphandles and an untrodden path in try_to_unuse (plus a few places added in this series). valid_swaphandles doesn't show up high in profiles, but swap_duplicate does demand attention. However, with the hold time in get_swap_pages so much reduced, I've not yet found a load and set of swap device priorities to show even swap_duplicate benefitting from the split. Certainly the split is mere overhead in the common case of a single swap device. So, replace swap_list_lock and swap_device_lock by spinlock_t swap_lock (generally we seem to prefer an _ in the name, and not hide in a macro). If someone can show a regression in swap_duplicate, then probably we should add a hashlock for the swap_map entries alone (shorts being anatomic), so as to help the case of the single swap device too. 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 'include/linux/swap.h')
-rw-r--r--include/linux/swap.h11
1 files changed, 2 insertions, 9 deletions
diff --git a/include/linux/swap.h b/include/linux/swap.h
index db3b5de7c92f..3c9ff0048153 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -121,7 +121,7 @@ enum {
121 */ 121 */
122struct swap_info_struct { 122struct swap_info_struct {
123 unsigned int flags; 123 unsigned int flags;
124 spinlock_t sdev_lock; 124 int prio; /* swap priority */
125 struct file *swap_file; 125 struct file *swap_file;
126 struct block_device *bdev; 126 struct block_device *bdev;
127 struct list_head extent_list; 127 struct list_head extent_list;
@@ -135,7 +135,6 @@ struct swap_info_struct {
135 unsigned int pages; 135 unsigned int pages;
136 unsigned int max; 136 unsigned int max;
137 unsigned int inuse_pages; 137 unsigned int inuse_pages;
138 int prio; /* swap priority */
139 int next; /* next entry on swap list */ 138 int next; /* next entry on swap list */
140}; 139};
141 140
@@ -221,13 +220,7 @@ extern int can_share_swap_page(struct page *);
221extern int remove_exclusive_swap_page(struct page *); 220extern int remove_exclusive_swap_page(struct page *);
222struct backing_dev_info; 221struct backing_dev_info;
223 222
224extern struct swap_list_t swap_list; 223extern spinlock_t swap_lock;
225extern spinlock_t swaplock;
226
227#define swap_list_lock() spin_lock(&swaplock)
228#define swap_list_unlock() spin_unlock(&swaplock)
229#define swap_device_lock(p) spin_lock(&p->sdev_lock)
230#define swap_device_unlock(p) spin_unlock(&p->sdev_lock)
231 224
232/* linux/mm/thrash.c */ 225/* linux/mm/thrash.c */
233extern struct mm_struct * swap_token_mm; 226extern struct mm_struct * swap_token_mm;