[PATCH v3 5/9] slab: introduce alien_cache
From: Joonsoo Kim
Date: Tue Jul 01 2014 - 04:26:13 EST
Currently, we use array_cache for alien_cache. Although they are mostly
similar, there is one difference, that is, need for spinlock.
We don't need spinlock for array_cache itself, but to use array_cache for
alien_cache, array_cache structure should have spinlock. This is needless
overhead, so removing it would be better. This patch prepare it by
introducing alien_cache and using it. In the following patch,
we remove spinlock in array_cache.
Acked-by: Christoph Lameter <cl@xxxxxxxxx>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
---
mm/slab.c | 108 ++++++++++++++++++++++++++++++++++++++-----------------------
mm/slab.h | 2 +-
2 files changed, 68 insertions(+), 42 deletions(-)
diff --git a/mm/slab.c b/mm/slab.c
index 00b6bbc..e1a473d 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -203,6 +203,11 @@ struct array_cache {
*/
};
+struct alien_cache {
+ spinlock_t lock;
+ struct array_cache ac;
+};
+
#define SLAB_OBJ_PFMEMALLOC 1
static inline bool is_obj_pfmemalloc(void *objp)
{
@@ -491,7 +496,7 @@ static void slab_set_lock_classes(struct kmem_cache *cachep,
struct lock_class_key *l3_key, struct lock_class_key *alc_key,
struct kmem_cache_node *n)
{
- struct array_cache **alc;
+ struct alien_cache **alc;
int r;
lockdep_set_class(&n->list_lock, l3_key);
@@ -507,7 +512,7 @@ static void slab_set_lock_classes(struct kmem_cache *cachep,
return;
for_each_node(r) {
if (alc[r])
- lockdep_set_class(&alc[r]->lock, alc_key);
+ lockdep_set_class(&(alc[r]->ac.lock), alc_key);
}
}
@@ -965,12 +970,13 @@ static int transfer_objects(struct array_cache *to,
#define drain_alien_cache(cachep, alien) do { } while (0)
#define reap_alien(cachep, n) do { } while (0)
-static inline struct array_cache **alloc_alien_cache(int node, int limit, gfp_t gfp)
+static inline struct alien_cache **alloc_alien_cache(int node,
+ int limit, gfp_t gfp)
{
- return (struct array_cache **)BAD_ALIEN_MAGIC;
+ return (struct alien_cache **)BAD_ALIEN_MAGIC;
}
-static inline void free_alien_cache(struct array_cache **ac_ptr)
+static inline void free_alien_cache(struct alien_cache **ac_ptr)
{
}
@@ -996,40 +1002,52 @@ static inline void *____cache_alloc_node(struct kmem_cache *cachep,
static void *____cache_alloc_node(struct kmem_cache *, gfp_t, int);
static void *alternate_node_alloc(struct kmem_cache *, gfp_t);
-static struct array_cache **alloc_alien_cache(int node, int limit, gfp_t gfp)
+static struct alien_cache *__alloc_alien_cache(int node, int entries,
+ int batch, gfp_t gfp)
+{
+ int memsize = sizeof(void *) * entries + sizeof(struct alien_cache);
+ struct alien_cache *alc = NULL;
+
+ alc = kmalloc_node(memsize, gfp, node);
+ init_arraycache(&alc->ac, entries, batch);
+ return alc;
+}
+
+static struct alien_cache **alloc_alien_cache(int node, int limit, gfp_t gfp)
{
- struct array_cache **ac_ptr;
+ struct alien_cache **alc_ptr;
int memsize = sizeof(void *) * nr_node_ids;
int i;
if (limit > 1)
limit = 12;
- ac_ptr = kzalloc_node(memsize, gfp, node);
- if (ac_ptr) {
- for_each_node(i) {
- if (i == node || !node_online(i))
- continue;
- ac_ptr[i] = alloc_arraycache(node, limit, 0xbaadf00d, gfp);
- if (!ac_ptr[i]) {
- for (i--; i >= 0; i--)
- kfree(ac_ptr[i]);
- kfree(ac_ptr);
- return NULL;
- }
+ alc_ptr = kzalloc_node(memsize, gfp, node);
+ if (!alc_ptr)
+ return NULL;
+
+ for_each_node(i) {
+ if (i == node || !node_online(i))
+ continue;
+ alc_ptr[i] = __alloc_alien_cache(node, limit, 0xbaadf00d, gfp);
+ if (!alc_ptr[i]) {
+ for (i--; i >= 0; i--)
+ kfree(alc_ptr[i]);
+ kfree(alc_ptr);
+ return NULL;
}
}
- return ac_ptr;
+ return alc_ptr;
}
-static void free_alien_cache(struct array_cache **ac_ptr)
+static void free_alien_cache(struct alien_cache **alc_ptr)
{
int i;
- if (!ac_ptr)
+ if (!alc_ptr)
return;
for_each_node(i)
- kfree(ac_ptr[i]);
- kfree(ac_ptr);
+ kfree(alc_ptr[i]);
+ kfree(alc_ptr);
}
static void __drain_alien_cache(struct kmem_cache *cachep,
@@ -1063,25 +1081,31 @@ static void reap_alien(struct kmem_cache *cachep, struct kmem_cache_node *n)
int node = __this_cpu_read(slab_reap_node);
if (n->alien) {
- struct array_cache *ac = n->alien[node];
-
- if (ac && ac->avail && spin_trylock_irq(&ac->lock)) {
- __drain_alien_cache(cachep, ac, node);
- spin_unlock_irq(&ac->lock);
+ struct alien_cache *alc = n->alien[node];
+ struct array_cache *ac;
+
+ if (alc) {
+ ac = &alc->ac;
+ if (ac->avail && spin_trylock_irq(&ac->lock)) {
+ __drain_alien_cache(cachep, ac, node);
+ spin_unlock_irq(&ac->lock);
+ }
}
}
}
static void drain_alien_cache(struct kmem_cache *cachep,
- struct array_cache **alien)
+ struct alien_cache **alien)
{
int i = 0;
+ struct alien_cache *alc;
struct array_cache *ac;
unsigned long flags;
for_each_online_node(i) {
- ac = alien[i];
- if (ac) {
+ alc = alien[i];
+ if (alc) {
+ ac = &alc->ac;
spin_lock_irqsave(&ac->lock, flags);
__drain_alien_cache(cachep, ac, i);
spin_unlock_irqrestore(&ac->lock, flags);
@@ -1093,7 +1117,8 @@ static inline int cache_free_alien(struct kmem_cache *cachep, void *objp)
{
int nodeid = page_to_nid(virt_to_page(objp));
struct kmem_cache_node *n;
- struct array_cache *alien = NULL;
+ struct alien_cache *alien = NULL;
+ struct array_cache *ac;
int node;
LIST_HEAD(list);
@@ -1110,13 +1135,14 @@ static inline int cache_free_alien(struct kmem_cache *cachep, void *objp)
STATS_INC_NODEFREES(cachep);
if (n->alien && n->alien[nodeid]) {
alien = n->alien[nodeid];
- spin_lock(&alien->lock);
- if (unlikely(alien->avail == alien->limit)) {
+ ac = &alien->ac;
+ spin_lock(&ac->lock);
+ if (unlikely(ac->avail == ac->limit)) {
STATS_INC_ACOVERFLOW(cachep);
- __drain_alien_cache(cachep, alien, nodeid);
+ __drain_alien_cache(cachep, ac, nodeid);
}
- ac_put_obj(cachep, alien, objp);
- spin_unlock(&alien->lock);
+ ac_put_obj(cachep, ac, objp);
+ spin_unlock(&ac->lock);
} else {
n = get_node(cachep, nodeid);
spin_lock(&n->list_lock);
@@ -1193,7 +1219,7 @@ static void cpuup_canceled(long cpu)
list_for_each_entry(cachep, &slab_caches, list) {
struct array_cache *nc;
struct array_cache *shared;
- struct array_cache **alien;
+ struct alien_cache **alien;
LIST_HEAD(list);
/* cpu is dead; no one can alloc from it. */
@@ -1275,7 +1301,7 @@ static int cpuup_prepare(long cpu)
list_for_each_entry(cachep, &slab_caches, list) {
struct array_cache *nc;
struct array_cache *shared = NULL;
- struct array_cache **alien = NULL;
+ struct alien_cache **alien = NULL;
if (memcg_cache_dead(cachep))
continue;
@@ -3799,7 +3825,7 @@ static int alloc_kmem_cache_node(struct kmem_cache *cachep, gfp_t gfp)
int node;
struct kmem_cache_node *n;
struct array_cache *new_shared;
- struct array_cache **new_alien = NULL;
+ struct alien_cache **new_alien = NULL;
for_each_online_node(node) {
diff --git a/mm/slab.h b/mm/slab.h
index 4789ca4..84c160a 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -301,7 +301,7 @@ struct kmem_cache_node {
unsigned int free_limit;
unsigned int colour_next; /* Per-node cache coloring */
struct array_cache *shared; /* shared per node */
- struct array_cache **alien; /* on other nodes */
+ struct alien_cache **alien; /* on other nodes */
unsigned long next_reap; /* updated without locking */
int free_touched; /* updated without locking */
#endif
--
1.7.9.5
--
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