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-rw-r--r--mm/slub.c58
1 files changed, 31 insertions, 27 deletions
diff --git a/mm/slub.c b/mm/slub.c
index 1e5a463..d97b692 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3358,11 +3358,12 @@ void kfree(const void *x)
}
EXPORT_SYMBOL(kfree);
+#define SHRINK_PROMOTE_MAX 32
+
/*
- * kmem_cache_shrink removes empty slabs from the partial lists and sorts
- * the remaining slabs by the number of items in use. The slabs with the
- * most items in use come first. New allocations will then fill those up
- * and thus they can be removed from the partial lists.
+ * kmem_cache_shrink discards empty slabs and promotes the slabs filled
+ * up most to the head of the partial lists. New allocations will then
+ * fill those up and thus they can be removed from the partial lists.
*
* The slabs with the least items are placed last. This results in them
* being allocated from last increasing the chance that the last objects
@@ -3375,51 +3376,57 @@ int __kmem_cache_shrink(struct kmem_cache *s)
struct kmem_cache_node *n;
struct page *page;
struct page *t;
- int objects = oo_objects(s->max);
- struct list_head *slabs_by_inuse =
- kmalloc(sizeof(struct list_head) * objects, GFP_KERNEL);
+ struct list_head discard;
+ struct list_head promote[SHRINK_PROMOTE_MAX];
unsigned long flags;
- if (!slabs_by_inuse)
- return -ENOMEM;
-
flush_all(s);
for_each_kmem_cache_node(s, node, n) {
if (!n->nr_partial)
continue;
- for (i = 0; i < objects; i++)
- INIT_LIST_HEAD(slabs_by_inuse + i);
+ INIT_LIST_HEAD(&discard);
+ for (i = 0; i < SHRINK_PROMOTE_MAX; i++)
+ INIT_LIST_HEAD(promote + i);
spin_lock_irqsave(&n->list_lock, flags);
/*
- * Build lists indexed by the items in use in each slab.
+ * Build lists of slabs to discard or promote.
*
* Note that concurrent frees may occur while we hold the
* list_lock. page->inuse here is the upper limit.
*/
list_for_each_entry_safe(page, t, &n->partial, lru) {
- list_move(&page->lru, slabs_by_inuse + page->inuse);
- if (!page->inuse)
+ int free = page->objects - page->inuse;
+
+ /* Do not reread page->inuse */
+ barrier();
+
+ /* We do not keep full slabs on the list */
+ BUG_ON(free <= 0);
+
+ if (free == page->objects) {
+ list_move(&page->lru, &discard);
n->nr_partial--;
+ } else if (free <= SHRINK_PROMOTE_MAX)
+ list_move(&page->lru, promote + free - 1);
}
/*
- * Rebuild the partial list with the slabs filled up most
- * first and the least used slabs at the end.
+ * Promote the slabs filled up most to the head of the
+ * partial list.
*/
- for (i = objects - 1; i > 0; i--)
- list_splice(slabs_by_inuse + i, n->partial.prev);
+ for (i = SHRINK_PROMOTE_MAX - 1; i >= 0; i--)
+ list_splice(promote + i, &n->partial);
spin_unlock_irqrestore(&n->list_lock, flags);
/* Release empty slabs */
- list_for_each_entry_safe(page, t, slabs_by_inuse, lru)
+ list_for_each_entry_safe(page, t, &discard, lru)
discard_slab(s, page);
}
- kfree(slabs_by_inuse);
return 0;
}
@@ -4686,12 +4693,9 @@ static ssize_t shrink_show(struct kmem_cache *s, char *buf)
static ssize_t shrink_store(struct kmem_cache *s,
const char *buf, size_t length)
{
- if (buf[0] == '1') {
- int rc = kmem_cache_shrink(s);
-
- if (rc)
- return rc;
- } else
+ if (buf[0] == '1')
+ kmem_cache_shrink(s);
+ else
return -EINVAL;
return length;
}

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