From 5d337b9194b1ce3b6fd5f3cb2799455ed2f9a3d1 Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Sat, 3 Sep 2005 15:54:41 -0700 Subject: [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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/swap.h | 11 ++--------- 1 file changed, 2 insertions(+), 9 deletions(-) (limited to 'include/linux/swap.h') 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 { */ struct swap_info_struct { unsigned int flags; - spinlock_t sdev_lock; + int prio; /* swap priority */ struct file *swap_file; struct block_device *bdev; struct list_head extent_list; @@ -135,7 +135,6 @@ struct swap_info_struct { unsigned int pages; unsigned int max; unsigned int inuse_pages; - int prio; /* swap priority */ int next; /* next entry on swap list */ }; @@ -221,13 +220,7 @@ extern int can_share_swap_page(struct page *); extern int remove_exclusive_swap_page(struct page *); struct backing_dev_info; -extern struct swap_list_t swap_list; -extern spinlock_t swaplock; - -#define swap_list_lock() spin_lock(&swaplock) -#define swap_list_unlock() spin_unlock(&swaplock) -#define swap_device_lock(p) spin_lock(&p->sdev_lock) -#define swap_device_unlock(p) spin_unlock(&p->sdev_lock) +extern spinlock_t swap_lock; /* linux/mm/thrash.c */ extern struct mm_struct * swap_token_mm; -- cgit v1.2.3-59-g8ed1b