[patch 10/10] SLUB: Restructure slab alloc

Christoph Lameter
2007-10-28T03:36:49Z

[-- Attachment #1: slub_restruct_alloc --]
[-- Type: text/plain, Size: 1817 bytes --]

Restructure slab_alloc so that the code flows in the sequence
it is usually executed.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

---
mm/slub.c | 40 ++++++++++++++++++++++++----------------
1 file changed, 24 insertions(+), 16 deletions(-)

Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c 2007-10-27 07:58:07.000000000 -0700
+++ linux-2.6/mm/slub.c 2007-10-27 07:58:36.000000000 -0700
@@ -1580,16 +1580,28 @@ static void *__slab_alloc(struct kmem_ca
local_irq_save(flags);
preempt_enable_no_resched();
#endif
- if (!c->page)
- goto new_slab;
+ if (likely(c->page)) {
+ state = slab_lock(c->page);
+
+ if (unlikely(node_match(c, node) &&
+ c->page->freelist != c->page->end))
+ goto load_freelist;
+
+ deactivate_slab(s, c, state);
+ }
+
+another_slab:
+ state = get_partial(s, c, gfpflags, node);
+ if (!state)
+ goto grow_slab;

- state = slab_lock(c->page);
- if (unlikely(!node_match(c, node)))
- goto another_slab;
load_freelist:
- object = c->page->freelist;
- if (unlikely(object == c->page->end))
- goto another_slab;
+ /*
+ * slabs from the partial list must have at least
+ * one free object.
+ */
+ VM_BUG_ON(c->page->freelist == c->page->end);
+
if (unlikely(state & SLABDEBUG))
goto debug;

@@ -1607,20 +1619,16 @@ out:
#endif
return object;

-another_slab:
- deactivate_slab(s, c, state);
-
-new_slab:
- state = get_partial(s, c, gfpflags, node);
- if (state)
- goto load_freelist;
-
+/* Extend the slabcache with a new slab */
+grow_slab:
state = get_new_slab(s, &c, gfpflags, node);
if (state)
goto load_freelist;

object = NULL;
goto out;
+
+/* Perform debugging */
debug:
object = c->page->freelist;
if (!alloc_debug_processing(s, c->page, object, addr))

--