From: Christoph Lameter <cl@linux.com>
To: Pekka Enberg <penberg@kernel.org>
Cc: linux-mm@kvack.org, David Rientjes <rientjes@google.com>
Subject: [Slub cleanup 3/9] slub: Acquire_slab() avoid loop
Date: Mon, 23 Jan 2012 14:16:49 -0600 [thread overview]
Message-ID: <20120123201707.186039210@linux.com> (raw)
In-Reply-To: 20120123201646.924319545@linux.com
[-- Attachment #1: simplify --]
[-- Type: text/plain, Size: 2148 bytes --]
Avoid the loop in acquire slab and simply fail if there is a conflict.
This will cause the next page on the list to be considered.
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
---
mm/slub.c | 28 +++++++++++++++-------------
1 file changed, 15 insertions(+), 13 deletions(-)
Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c 2012-01-13 08:47:10.938748802 -0600
+++ linux-2.6/mm/slub.c 2012-01-13 08:47:17.158748674 -0600
@@ -1484,12 +1484,12 @@ static inline void remove_partial(struct
}
/*
- * Lock slab, remove from the partial list and put the object into the
- * per cpu freelist.
+ * Remove slab from the partial list, freeze it and
+ * return the pointer to the freelist.
*
* Returns a list of objects or NULL if it fails.
*
- * Must hold list_lock.
+ * Must hold list_lock since we modify the partial list.
*/
static inline void *acquire_slab(struct kmem_cache *s,
struct kmem_cache_node *n, struct page *page,
@@ -1504,22 +1504,24 @@ static inline void *acquire_slab(struct
* The old freelist is the list of objects for the
* per cpu allocation list.
*/
- do {
- freelist = page->freelist;
- counters = page->counters;
- new.counters = counters;
- if (mode)
- new.inuse = page->objects;
+ freelist = page->freelist;
+ counters = page->counters;
+ new.counters = counters;
+ if (mode)
+ new.inuse = page->objects;
- VM_BUG_ON(new.frozen);
- new.frozen = 1;
+ VM_BUG_ON(new.frozen);
+ new.frozen = 1;
- } while (!__cmpxchg_double_slab(s, page,
+ if (!__cmpxchg_double_slab(s, page,
freelist, counters,
NULL, new.counters,
- "lock and freeze"));
+ "acquire_slab"))
+
+ return NULL;
remove_partial(n, page);
+ WARN_ON(!freelist);
return freelist;
}
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next prev parent reply other threads:[~2012-01-23 20:17 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-23 20:16 [Slub cleanup 0/9] Slub: cleanups V1 Christoph Lameter
2012-01-23 20:16 ` [Slub cleanup 1/9] slub: Use freelist instead of "object" in __slab_alloc Christoph Lameter
2012-02-01 21:51 ` David Rientjes
2012-01-23 20:16 ` [Slub cleanup 2/9] slub: Add frozen check " Christoph Lameter
2012-02-01 21:54 ` David Rientjes
2012-01-23 20:16 ` Christoph Lameter [this message]
2012-01-23 20:16 ` [Slub cleanup 4/9] slub: Simplify control flow in __slab_alloc() Christoph Lameter
2012-02-01 22:02 ` David Rientjes
2012-01-23 20:16 ` [Slub cleanup 6/9] slub: Get rid of the node field Christoph Lameter
2012-02-01 22:11 ` David Rientjes
2012-01-23 20:16 ` [Slub cleanup 7/9] slub: Separate out kmem_cache_cpu processing from deactivate_slab Christoph Lameter
2012-01-23 20:16 ` [Slub cleanup 8/9] slub: Use page variable instead of c->page Christoph Lameter
2012-01-23 20:16 ` [Slub cleanup 9/9] slub: pass page to node_match() instead of kmem_cache_cpu structure Christoph Lameter
[not found] ` <20120123201708.312262597@linux.com>
2012-02-01 22:05 ` [Slub cleanup 5/9] slub: new_slab_objects() can also get objects from partial list David Rientjes
-- strict thread matches above, loose matches on Subject: below --
2012-05-09 15:09 [Slub cleanup 0/9] Slub: cleanups V2 cl, Christoph Lameter
2012-05-09 15:09 ` [Slub cleanup 3/9] slub: Acquire_slab() avoid loop cl, Christoph Lameter
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