The only concern of introducing partial counter is that,
partial_free_objs may cause cache and atomic operation
contention in case of same SLUB concurrent __slab_free().
This patch changes it to be a percpu counter, also replace
the counter variables to avoid cacheline issues.
Tested-by: James Wang <jnw...@linux.alibaba.com>
Reviewed-by: Pekka Enberg <penb...@kernel.org>
Signed-off-by: Xunlei Pang <xlp...@linux.alibaba.com>
---
mm/slab.h | 6 ++++--
mm/slub.c | 30 +++++++++++++++++++++++-------
2 files changed, 27 insertions(+), 9 deletions(-)
diff --git a/mm/slab.h b/mm/slab.h
index 817bfa0..c819597 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -546,16 +546,18 @@ struct kmem_cache_node {
#ifdef CONFIG_SLUB
unsigned long nr_partial;
- struct list_head partial;
#if defined(CONFIG_SLUB_DEBUG) || defined(CONFIG_SYSFS)
- atomic_long_t partial_free_objs;
unsigned long partial_total_objs;
#endif
+ struct list_head partial;
#ifdef CONFIG_SLUB_DEBUG
atomic_long_t nr_slabs;
atomic_long_t total_objects;
struct list_head full;
#endif
+#if defined(CONFIG_SLUB_DEBUG) || defined(CONFIG_SYSFS)
+ unsigned long __percpu *partial_free_objs;
+#endif
#endif
};
diff --git a/mm/slub.c b/mm/slub.c
index 3f76b57..b6ec065 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1894,7 +1894,7 @@ static void discard_slab(struct kmem_cache *s, struct
page *page)
static inline void
__update_partial_free(struct kmem_cache_node *n, long delta)
{
- atomic_long_add(delta, &n->partial_free_objs);
+ this_cpu_add(*n->partial_free_objs, delta);
}
static inline void
@@ -2548,11 +2548,16 @@ 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 = per_cpu_sum(*n->partial_free_objs);
+ if ((long)ret < 0)
+ ret = 0;
} else if (item == PARTIAL_TOTAL) {
ret = n->partial_total_objs;
} else if (item == PARTIAL_INUSE) {
- ret = n->partial_total_objs -
atomic_long_read(&n->partial_free_objs);
+ ret = per_cpu_sum(*n->partial_free_objs);
+ if ((long)ret < 0)
+ ret = 0;
+ ret = n->partial_total_objs - ret;
if ((long)ret < 0)
ret = 0;
}
@@ -3552,14 +3557,16 @@ static inline int calculate_order(unsigned int size)
return -ENOSYS;
}
-static void
+static int
init_kmem_cache_node(struct kmem_cache_node *n)
{
n->nr_partial = 0;
spin_lock_init(&n->list_lock);
INIT_LIST_HEAD(&n->partial);
#if defined(CONFIG_SLUB_DEBUG) || defined(CONFIG_SYSFS)
- atomic_long_set(&n->partial_free_objs, 0);
+ n->partial_free_objs = alloc_percpu(unsigned long);
+ if (!n->partial_free_objs)
+ return -ENOMEM;
n->partial_total_objs = 0;
#endif
#ifdef CONFIG_SLUB_DEBUG
@@ -3567,6 +3574,8 @@ static inline int calculate_order(unsigned int size)
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)
@@ -3626,7 +3635,7 @@ 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);
/*
@@ -3644,6 +3653,9 @@ static void free_kmem_cache_nodes(struct kmem_cache *s)
for_each_kmem_cache_node(s, node, n) {
s->node[node] = NULL;
+#if defined(CONFIG_SLUB_DEBUG) || defined(CONFIG_SYSFS)
+ free_percpu(n->partial_free_objs);
+#endif
kmem_cache_free(kmem_cache_node, n);
}
}
@@ -3674,7 +3686,11 @@ 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
