[PATCH v2 07/10] slab: use the lock on alien_cache, instead of the lock on array_cache

From: Joonsoo Kim
Date: Wed May 07 2014 - 02:04:49 EST


Now, we have separate alien_cache structure, so it'd be better to hold
the lock on alien_cache while manipulating alien_cache. After that,
we don't need the lock on array_cache, so remove it.

Acked-by: Christoph Lameter <cl@xxxxxxxxx>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>

diff --git a/mm/slab.c b/mm/slab.c
index 41b7651..889957b 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -191,7 +191,6 @@ struct array_cache {
unsigned int limit;
unsigned int batchcount;
unsigned int touched;
- spinlock_t lock;
void *entry[]; /*
* Must have this definition in here for the proper
* alignment of array_cache. Also simplifies accessing
@@ -484,7 +483,7 @@ static void slab_set_lock_classes(struct kmem_cache *cachep,
return;
for_each_node(r) {
if (alc[r])
- lockdep_set_class(&(alc[r]->ac.lock), alc_key);
+ lockdep_set_class(&(alc[r]->lock), alc_key);
}
}

@@ -761,7 +760,6 @@ static void init_arraycache(struct array_cache *ac, int limit, int batch)
ac->limit = limit;
ac->batchcount = batch;
ac->touched = 0;
- spin_lock_init(&ac->lock);
}
}

@@ -957,6 +955,7 @@ static struct alien_cache *__alloc_alien_cache(int node, int entries,

alc = kmalloc_node(memsize, gfp, node);
init_arraycache(&alc->ac, entries, batch);
+ spin_lock_init(&alc->lock);
return alc;
}

@@ -1033,9 +1032,9 @@ static void reap_alien(struct kmem_cache *cachep, struct kmem_cache_node *n)

if (alc) {
ac = &alc->ac;
- if (ac->avail && spin_trylock_irq(&ac->lock)) {
+ if (ac->avail && spin_trylock_irq(&alc->lock)) {
__drain_alien_cache(cachep, ac, node);
- spin_unlock_irq(&ac->lock);
+ spin_unlock_irq(&alc->lock);
}
}
}
@@ -1053,9 +1052,9 @@ static void drain_alien_cache(struct kmem_cache *cachep,
alc = alien[i];
if (alc) {
ac = &alc->ac;
- spin_lock_irqsave(&ac->lock, flags);
+ spin_lock_irqsave(&alc->lock, flags);
__drain_alien_cache(cachep, ac, i);
- spin_unlock_irqrestore(&ac->lock, flags);
+ spin_unlock_irqrestore(&alc->lock, flags);
}
}
}
@@ -1083,13 +1082,13 @@ static inline int cache_free_alien(struct kmem_cache *cachep, void *objp)
if (n->alien && n->alien[nodeid]) {
alien = n->alien[nodeid];
ac = &alien->ac;
- spin_lock(&ac->lock);
+ spin_lock(&alien->lock);
if (unlikely(ac->avail == ac->limit)) {
STATS_INC_ACOVERFLOW(cachep);
__drain_alien_cache(cachep, ac, nodeid);
}
ac_put_obj(cachep, ac, objp);
- spin_unlock(&ac->lock);
+ spin_unlock(&alien->lock);
} else {
spin_lock(&(cachep->node[nodeid])->list_lock);
free_block(cachep, &objp, 1, nodeid, &list);
@@ -1558,10 +1557,6 @@ void __init kmem_cache_init(void)

memcpy(ptr, cpu_cache_get(kmem_cache),
sizeof(struct arraycache_init));
- /*
- * Do not assume that spinlocks can be initialized via memcpy:
- */
- spin_lock_init(&ptr->lock);

kmem_cache->array[smp_processor_id()] = ptr;

@@ -1571,10 +1566,6 @@ void __init kmem_cache_init(void)
!= &initarray_generic.cache);
memcpy(ptr, cpu_cache_get(kmalloc_caches[INDEX_AC]),
sizeof(struct arraycache_init));
- /*
- * Do not assume that spinlocks can be initialized via memcpy:
- */
- spin_lock_init(&ptr->lock);

kmalloc_caches[INDEX_AC]->array[smp_processor_id()] = ptr;
}
--
1.7.9.5

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