[PATCH] slab: add transfer_objects() function
slabr_objects() can be used to transfer objects between various object
caches of the slab allocator. It is currently only used during
__cache_alloc() to retrieve elements from the shared array. We will be
using it soon to transfer elements from the alien caches to the remote
shared array.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/mm/slab.c b/mm/slab.c
index 6a3760e..dee857a 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -898,6 +898,30 @@
return nc;
}
+/*
+ * Transfer objects in one arraycache to another.
+ * Locking must be handled by the caller.
+ *
+ * Return the number of entries transferred.
+ */
+static int transfer_objects(struct array_cache *to,
+ struct array_cache *from, unsigned int max)
+{
+ /* Figure out how many entries to transfer */
+ int nr = min(min(from->avail, max), to->limit - to->avail);
+
+ if (!nr)
+ return 0;
+
+ memcpy(to->entry + to->avail, from->entry + from->avail -nr,
+ sizeof(void *) *nr);
+
+ from->avail -= nr;
+ to->avail += nr;
+ to->touched = 1;
+ return nr;
+}
+
#ifdef CONFIG_NUMA
static void *__cache_alloc_node(struct kmem_cache *, gfp_t, int);
static void *alternate_node_alloc(struct kmem_cache *, gfp_t);
@@ -2680,20 +2704,10 @@
BUG_ON(ac->avail > 0 || !l3);
spin_lock(&l3->list_lock);
- if (l3->shared) {
- struct array_cache *shared_array = l3->shared;
- if (shared_array->avail) {
- if (batchcount > shared_array->avail)
- batchcount = shared_array->avail;
- shared_array->avail -= batchcount;
- ac->avail = batchcount;
- memcpy(ac->entry,
- &(shared_array->entry[shared_array->avail]),
- sizeof(void *) * batchcount);
- shared_array->touched = 1;
- goto alloc_done;
- }
- }
+ /* See if we can refill from the shared array */
+ if (l3->shared && transfer_objects(ac, l3->shared, batchcount))
+ goto alloc_done;
+
while (batchcount > 0) {
struct list_head *entry;
struct slab *slabp;
