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Date: Mon, 14 May 2007 10:50:54 +1000
From: Con Kolivas <kernel@...ivas.org>
To: linux-kernel@...r.kernel.org, linux-mm@...ck.org,
Andrew Morton <akpm@...ux-foundation.org>, ck@....kolivas.org
Subject: [PATCH] mm: swap prefetch more improvements
akpm, please queue on top of "mm: swap prefetch improvements"
---
Failed radix_tree_insert wasn't being handled leaving stale kmem.
The list should be iterated over in the reverse order when prefetching.
Make the yield within kprefetchd stronger through the use of cond_resched.
Check that the pos entry hasn't been removed while unlocked.
Signed-off-by: Con Kolivas <kernel@...ivas.org>
---
mm/swap_prefetch.c | 19 ++++++++++---------
1 file changed, 10 insertions(+), 9 deletions(-)
Index: linux-2.6.21-ck1/mm/swap_prefetch.c
===================================================================
--- linux-2.6.21-ck1.orig/mm/swap_prefetch.c 2007-05-14 09:39:37.000000000 +1000
+++ linux-2.6.21-ck1/mm/swap_prefetch.c 2007-05-14 10:21:47.000000000 +1000
@@ -117,7 +117,8 @@ void add_to_swapped_list(struct page *pa
if (likely(!radix_tree_insert(&swapped.swap_tree, index, entry))) {
list_add(&entry->swapped_list, &swapped.list);
swapped.count++;
- }
+ } else
+ kmem_cache_free(swapped.cache, entry);
out_locked:
spin_unlock_irqrestore(&swapped.lock, flags);
@@ -427,7 +428,7 @@ out:
static enum trickle_return trickle_swap(void)
{
enum trickle_return ret = TRICKLE_DELAY;
- struct list_head *p, *next;
+ struct swapped_entry *pos, *n;
unsigned long flags;
if (!prefetch_enabled())
@@ -440,19 +441,19 @@ static enum trickle_return trickle_swap(
return TRICKLE_FAILED;
spin_lock_irqsave(&swapped.lock, flags);
- list_for_each_safe(p, next, &swapped.list) {
- struct swapped_entry *entry;
+ list_for_each_entry_safe_reverse(pos, n, &swapped.list, swapped_list) {
swp_entry_t swp_entry;
int node;
spin_unlock_irqrestore(&swapped.lock, flags);
- might_sleep();
- if (!prefetch_suitable())
+ /* Yield to anything else running */
+ if (cond_resched() || !prefetch_suitable())
goto out_unlocked;
spin_lock_irqsave(&swapped.lock, flags);
- entry = list_entry(p, struct swapped_entry, swapped_list);
- node = get_swap_entry_node(entry);
+ if (unlikely(!pos))
+ continue;
+ node = get_swap_entry_node(pos);
if (!node_isset(node, sp_stat.prefetch_nodes)) {
/*
* We found an entry that belongs to a node that is
@@ -460,7 +461,7 @@ static enum trickle_return trickle_swap(
*/
continue;
}
- swp_entry = entry->swp_entry;
+ swp_entry = pos->swp_entry;
spin_unlock_irqrestore(&swapped.lock, flags);
if (trickle_swap_cache_async(swp_entry, node) == TRICKLE_DELAY)
--
-ck
-
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