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swap: make each swap partition have one address_space

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When I use several fast SSD to do swap, swapper_space.tree_lock is
heavily contended.  This makes each swap partition have one
address_space to reduce the lock contention.  There is an array of
address_space for swap.  The swap entry type is the index to the array.

In my test with 3 SSD, this increases the swapout throughput 20%.

[akpm@linux-foundation.org: revert unneeded change to  __add_to_swap_cache]
Signed-off-by: Shaohua Li <shli@fusionio.com>
Cc: Hugh Dickins <hughd@google.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Shaohua Li
2013-02-22 16:34:37 -08:00
committed by Linus Torvalds
parent 9800339b5e
commit 33806f06da
8 changed files with 67 additions and 34 deletions
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5
mm/mincore.c
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@@ -75,7 +75,7 @@ static unsigned char mincore_page(struct address_space *mapping, pgoff_t pgoff)
/* shmem/tmpfs may return swap: account for swapcache page too. */
if (radix_tree_exceptional_entry(page)) {
swp_entry_t swap = radix_to_swp_entry(page);
page = find_get_page(&swapper_space, swap.val);
page = find_get_page(swap_address_space(swap), swap.val);
}
#endif
if (page) {
@@ -135,7 +135,8 @@ static void mincore_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
} else {
#ifdef CONFIG_SWAP
pgoff = entry.val;
*vec = mincore_page(&swapper_space, pgoff);
*vec = mincore_page(swap_address_space(entry),
pgoff);
#else
WARN_ON(1);
*vec = 1;