slub: move min_partial to struct kmem_cache

Although it allows for better cacheline use, it is unnecessary to save a
copy of the cache's min_partial value in each kmem_cache_node.

Cc: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>

include/linux/slub_def.h

@@ -46,7 +46,6 @@ struct kmem_cache_cpu {
 struct kmem_cache_node {
 	spinlock_t list_lock;	/* Protect partial list and nr_partial */
 	unsigned long nr_partial;
-	unsigned long min_partial;
 	struct list_head partial;
 #ifdef CONFIG_SLUB_DEBUG
 	atomic_long_t nr_slabs;
@@ -89,6 +88,7 @@ struct kmem_cache {
 	void (*ctor)(void *);
 	int inuse;		/* Offset to metadata */
 	int align;		/* Alignment */
+	unsigned long min_partial;
 	const char *name;	/* Name (only for display!) */
 	struct list_head list;	/* List of slab caches */
 #ifdef CONFIG_SLUB_DEBUG

mm/slub.c

@@ -1335,7 +1335,7 @@ static struct page *get_any_partial(struct kmem_cache *s, gfp_t flags)
 		n = get_node(s, zone_to_nid(zone));
 
 		if (n && cpuset_zone_allowed_hardwall(zone, flags) &&
-				n->nr_partial > n->min_partial) {
+				n->nr_partial > s->min_partial) {
 			page = get_partial_node(n);
 			if (page)
 				return page;
@@ -1387,7 +1387,7 @@ static void unfreeze_slab(struct kmem_cache *s, struct page *page, int tail)
 		slab_unlock(page);
 	} else {
 		stat(c, DEACTIVATE_EMPTY);
-		if (n->nr_partial < n->min_partial) {
+		if (n->nr_partial < s->min_partial) {
 			/*
 			 * Adding an empty slab to the partial slabs in order
 			 * to avoid page allocator overhead. This slab needs
@@ -1928,17 +1928,6 @@ static void
 init_kmem_cache_node(struct kmem_cache_node *n, struct kmem_cache *s)
 {
 	n->nr_partial = 0;
-
-	/*
-	 * The larger the object size is, the more pages we want on the partial
-	 * list to avoid pounding the page allocator excessively.
-	 */
-	n->min_partial = ilog2(s->size);
-	if (n->min_partial < MIN_PARTIAL)
-		n->min_partial = MIN_PARTIAL;
-	else if (n->min_partial > MAX_PARTIAL)
-		n->min_partial = MAX_PARTIAL;
-
 	spin_lock_init(&n->list_lock);
 	INIT_LIST_HEAD(&n->partial);
 #ifdef CONFIG_SLUB_DEBUG
@@ -2181,6 +2170,15 @@ static int init_kmem_cache_nodes(struct kmem_cache *s, gfp_t gfpflags)
 }
 #endif
 
+static void calculate_min_partial(struct kmem_cache *s, unsigned long min)
+{
+	if (min < MIN_PARTIAL)
+		min = MIN_PARTIAL;
+	else if (min > MAX_PARTIAL)
+		min = MAX_PARTIAL;
+	s->min_partial = min;
+}
+
 /*
  * calculate_sizes() determines the order and the distribution of data within
  * a slab object.
@@ -2319,6 +2317,11 @@ static int kmem_cache_open(struct kmem_cache *s, gfp_t gfpflags,
 	if (!calculate_sizes(s, -1))
 		goto error;
 
+	/*
+	 * The larger the object size is, the more pages we want on the partial
+	 * list to avoid pounding the page allocator excessively.
+	 */
+	calculate_min_partial(s, ilog2(s->size));
 	s->refcount = 1;
 #ifdef CONFIG_NUMA
 	s->remote_node_defrag_ratio = 1000;