The only concern of introducing partial counter is that,
partial_free_objs may cause atomic operation contention
in case of same SLUB concurrent __slab_free().
This patch changes it to be a percpu counter to avoid that.
Co-developed-by: Wen Yang <weny...@linux.alibaba.com>
Signed-off-by: Xunlei Pang <xlp...@linux.alibaba.com>
---
mm/slab.h | 2 +-
mm/slub.c | 38 +++++++++++++++++++++++++++++++-------
2 files changed, 32 insertions(+), 8 deletions(-)
diff --git a/mm/slab.h b/mm/slab.h
index c85e2fa..a709a70 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -616,7 +616,7 @@ struct kmem_cache_node {
#ifdef CONFIG_SLUB
unsigned long nr_partial;
struct list_head partial;
- atomic_long_t partial_free_objs;
+ atomic_long_t __percpu *partial_free_objs;
atomic_long_t partial_total_objs;
#ifdef CONFIG_SLUB_DEBUG
atomic_long_t nr_slabs;
diff --git a/mm/slub.c b/mm/slub.c
index 25a4421..f6fc60b 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1775,11 +1775,21 @@ static void discard_slab(struct kmem_cache *s, struct
page *page)
/*
* Management of partially allocated slabs.
*/
+static inline long get_partial_free(struct kmem_cache_node *n)
+{
+ long nr = 0;
+ int cpu;
+
+ for_each_possible_cpu(cpu)
+ nr += atomic_long_read(per_cpu_ptr(n->partial_free_objs, cpu));
+
+ return nr;
+}
static inline void
__update_partial_free(struct kmem_cache_node *n, long delta)
{
- atomic_long_add(delta, &n->partial_free_objs);
+ atomic_long_add(delta, this_cpu_ptr(n->partial_free_objs));
}
static inline void
@@ -2429,12 +2439,12 @@ static unsigned long partial_counter(struct
kmem_cache_node *n,
unsigned long ret = 0;
if (item == PARTIAL_FREE) {
- ret = atomic_long_read(&n->partial_free_objs);
+ ret = get_partial_free(n);
} else if (item == PARTIAL_TOTAL) {
ret = atomic_long_read(&n->partial_total_objs);
} else if (item == PARTIAL_INUSE) {
ret = atomic_long_read(&n->partial_total_objs) -
- atomic_long_read(&n->partial_free_objs);
+ get_partial_free(n);
if ((long)ret < 0)
ret = 0;
}
@@ -3390,19 +3400,28 @@ static inline int calculate_order(unsigned int size)
return -ENOSYS;
}
-static void
+static int
init_kmem_cache_node(struct kmem_cache_node *n)
{
+ int cpu;
+
n->nr_partial = 0;
spin_lock_init(&n->list_lock);
INIT_LIST_HEAD(&n->partial);
- atomic_long_set(&n->partial_free_objs, 0);
+
+ n->partial_free_objs = alloc_percpu(atomic_long_t);
+ if (!n->partial_free_objs)
+ return -ENOMEM;
+ for_each_possible_cpu(cpu)
+ atomic_long_set(per_cpu_ptr(n->partial_free_objs, cpu), 0);
atomic_long_set(&n->partial_total_objs, 0);
#ifdef CONFIG_SLUB_DEBUG
atomic_long_set(&n->nr_slabs, 0);
atomic_long_set(&n->total_objects, 0);
INIT_LIST_HEAD(&n->full);
#endif
+
+ return 0;
}
static inline int alloc_kmem_cache_cpus(struct kmem_cache *s)
@@ -3463,7 +3482,7 @@ static void early_kmem_cache_node_alloc(int node)
page->inuse = 1;
page->frozen = 0;
kmem_cache_node->node[node] = n;
- init_kmem_cache_node(n);
+ BUG_ON(init_kmem_cache_node(n) < 0);
inc_slabs_node(kmem_cache_node, node, page->objects);
/*
@@ -3481,6 +3500,7 @@ static void free_kmem_cache_nodes(struct kmem_cache *s)
for_each_kmem_cache_node(s, node, n) {
s->node[node] = NULL;
+ free_percpu(n->partial_free_objs);
kmem_cache_free(kmem_cache_node, n);
}
}
@@ -3511,7 +3531,11 @@ static int init_kmem_cache_nodes(struct kmem_cache *s)
return 0;
}
- init_kmem_cache_node(n);
+ if (init_kmem_cache_node(n) < 0) {
+ free_kmem_cache_nodes(s);
+ return 0;
+ }
+
s->node[node] = n;
}
return 1;
--
1.8.3.1
