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Subject[patch 2/2]slub: add a type for slab partial list position
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Adding slab to partial list head/tail is sensentive to performance.
So adding a type to document it to avoid we get it wrong.

Signed-off-by: Shaohua Li <shli@kernel.org>
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
---
mm/slub.c | 20 +++++++++++++-------
1 file changed, 13 insertions(+), 7 deletions(-)

Index: linux/mm/slub.c
===================================================================
--- linux.orig/mm/slub.c 2011-08-23 08:20:24.000000000 +0800
+++ linux/mm/slub.c 2011-08-23 08:34:29.000000000 +0800
@@ -1525,16 +1525,21 @@ static void discard_slab(struct kmem_cac
free_slab(s, page);
}

+enum partial_list_position {
+ PARTIAL_LIST_HEAD,
+ PARTIAL_LIST_TAIL,
+};
+
/*
* Management of partially allocated slabs.
*
* list_lock must be held.
*/
static inline void add_partial(struct kmem_cache_node *n,
- struct page *page, int tail)
+ struct page *page, enum partial_list_position tail)
{
n->nr_partial++;
- if (tail)
+ if (tail == PARTIAL_LIST_TAIL)
list_add_tail(&page->lru, &n->partial);
else
list_add(&page->lru, &n->partial);
@@ -1781,13 +1786,13 @@ static void deactivate_slab(struct kmem_
enum slab_modes l = M_NONE, m = M_NONE;
void *freelist;
void *nextfree;
- int tail = 0;
+ enum partial_list_position tail = PARTIAL_LIST_HEAD;
struct page new;
struct page old;

if (page->freelist) {
stat(s, DEACTIVATE_REMOTE_FREES);
- tail = 1;
+ tail = PARTIAL_LIST_TAIL;
}

c->tid = next_tid(c->tid);
@@ -1893,7 +1898,8 @@ redo:
if (m == M_PARTIAL) {

add_partial(n, page, tail);
- stat(s, tail ? DEACTIVATE_TO_TAIL : DEACTIVATE_TO_HEAD);
+ stat(s, tail == PARTIAL_LIST_TAIL ? DEACTIVATE_TO_TAIL
+ : DEACTIVATE_TO_HEAD);

} else if (m == M_FULL) {

@@ -2377,7 +2383,7 @@ static void __slab_free(struct kmem_cach
*/
if (unlikely(!prior)) {
remove_full(s, page);
- add_partial(n, page, 1);
+ add_partial(n, page, PARTIAL_LIST_TAIL);
stat(s, FREE_ADD_PARTIAL);
}
}
@@ -2695,7 +2701,7 @@ static void early_kmem_cache_node_alloc(
init_kmem_cache_node(n, kmem_cache_node);
inc_slabs_node(kmem_cache_node, node, page->objects);

- add_partial(n, page, 0);
+ add_partial(n, page, PARTIAL_LIST_HEAD);
}

static void free_kmem_cache_nodes(struct kmem_cache *s)



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