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authorHugh Dickins <hugh@veritas.com>2005-09-03 15:54:41 -0700
committerLinus Torvalds <torvalds@evo.osdl.org>2005-09-05 00:05:42 -0700
commit5d337b9194b1ce3b6fd5f3cb2799455ed2f9a3d1 (patch)
tree91ed9ef6f4cb5f6a1832f2baaaabd53fcd83513e /mm/rmap.c
parent048c27fd72816b44e096997d1c6901c3abbfd45b (diff)
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[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 'mm/rmap.c')
-rw-r--r--mm/rmap.c3
1 files changed, 1 insertions, 2 deletions
diff --git a/mm/rmap.c b/mm/rmap.c
index 08ac5c7..facb8cd 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -34,9 +34,8 @@
* anon_vma->lock
* mm->page_table_lock
* zone->lru_lock (in mark_page_accessed)
- * swap_list_lock (in swap_free etc's swap_info_get)
+ * swap_lock (in swap_duplicate, swap_info_get)
* mmlist_lock (in mmput, drain_mmlist and others)
- * swap_device_lock (in swap_duplicate, swap_info_get)
* mapping->private_lock (in __set_page_dirty_buffers)
* inode_lock (in set_page_dirty's __mark_inode_dirty)
* sb_lock (within inode_lock in fs/fs-writeback.c)