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authorHugh Dickins <hugh@veritas.com>2005-09-04 00:54:41 +0200
committerLinus Torvalds <torvalds@evo.osdl.org>2005-09-05 09:05:42 +0200
commit5d337b9194b1ce3b6fd5f3cb2799455ed2f9a3d1 (patch)
tree91ed9ef6f4cb5f6a1832f2baaaabd53fcd83513e /include/asm-frv/stat.h
parent[PATCH] swap: scan_swap_map latency breaks (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>
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