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authorHugh Dickins <hugh@veritas.com>2005-09-04 02:54:41 +0400
committerLinus Torvalds <torvalds@evo.osdl.org>2005-09-05 11:05:42 +0400
commit5d337b9194b1ce3b6fd5f3cb2799455ed2f9a3d1 (patch)
tree91ed9ef6f4cb5f6a1832f2baaaabd53fcd83513e /mm/filemap.c
parent048c27fd72816b44e096997d1c6901c3abbfd45b (diff)
downloadlinux-5d337b9194b1ce3b6fd5f3cb2799455ed2f9a3d1.tar.xz
[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/filemap.c')
-rw-r--r--mm/filemap.c7
1 files changed, 3 insertions, 4 deletions
diff --git a/mm/filemap.c b/mm/filemap.c
index c11418dd94e8..edc54436fa94 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -54,9 +54,8 @@
*
* ->i_mmap_lock (vmtruncate)
* ->private_lock (__free_pte->__set_page_dirty_buffers)
- * ->swap_list_lock
- * ->swap_device_lock (exclusive_swap_page, others)
- * ->mapping->tree_lock
+ * ->swap_lock (exclusive_swap_page, others)
+ * ->mapping->tree_lock
*
* ->i_sem
* ->i_mmap_lock (truncate->unmap_mapping_range)
@@ -86,7 +85,7 @@
* ->page_table_lock (anon_vma_prepare and various)
*
* ->page_table_lock
- * ->swap_device_lock (try_to_unmap_one)
+ * ->swap_lock (try_to_unmap_one)
* ->private_lock (try_to_unmap_one)
* ->tree_lock (try_to_unmap_one)
* ->zone.lru_lock (follow_page->mark_page_accessed)