transfer_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 <[email protected]>
Index: linux-2.6.16-rc6-mm2/mm/slab.c
===================================================================
--- linux-2.6.16-rc6-mm2.orig/mm/slab.c 2006-03-21 14:52:47.000000000 -0800
+++ linux-2.6.16-rc6-mm2/mm/slab.c 2006-03-21 14:53:40.000000000 -0800
@@ -901,6 +901,30 @@ static struct array_cache *alloc_arrayca
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, 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);
@@ -2684,20 +2708,10 @@ retry:
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;
-
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