Re: [PATCH v3 13/28] slub: create duplicate cache
From: Christoph Lameter <hidden>
Date: 2012-05-29 14:37:03
Also in:
linux-mm, lkml
On Fri, 25 May 2012, Glauber Costa wrote:
quoted hunk ↗ jump to hunk
index dacd1fb..4689034 100644--- a/mm/memcontrol.c +++ b/mm/memcontrol.c@@ -467,6 +467,23 @@ struct cg_proto *tcp_proto_cgroup(struct mem_cgroup *memcg) EXPORT_SYMBOL(tcp_proto_cgroup); #endif /* CONFIG_INET */ +char *mem_cgroup_cache_name(struct mem_cgroup *memcg, struct kmem_cache *cachep) +{ + char *name; + struct dentry *dentry; + + rcu_read_lock(); + dentry = rcu_dereference(memcg->css.cgroup->dentry); + rcu_read_unlock(); + + BUG_ON(dentry == NULL); + + name = kasprintf(GFP_KERNEL, "%s(%d:%s)", + cachep->name, css_id(&memcg->css), dentry->d_name.name); + + return name; +}
Function allocates a string that is supposed to be disposed of by the caller. That needs to be documented and maybe even the name needs to reflect that.
quoted hunk ↗ jump to hunk
--- a/mm/slub.c +++ b/mm/slub.c@@ -4002,6 +4002,38 @@ struct kmem_cache *kmem_cache_create(const char *name, size_t size, } EXPORT_SYMBOL(kmem_cache_create); +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM +struct kmem_cache *kmem_cache_dup(struct mem_cgroup *memcg, + struct kmem_cache *s) +{ + char *name; + struct kmem_cache *new; + + name = mem_cgroup_cache_name(memcg, s); + if (!name) + return NULL; + + new = kmem_cache_create_memcg(memcg, name, s->objsize, s->align, + (s->allocflags & ~SLAB_PANIC), s->ctor);
Hmmm... A full duplicate of the slab cache? We may have many sparsely used portions of the per node and per cpu structure as a result.
+ * prevent it from being deleted. If kmem_cache_destroy() is
+ * called for the root cache before we call it for a child cache,
+ * it will be queued for destruction when we finally drop the
+ * reference on the child cache.
+ */
+ if (new) {
+ down_write(&slub_lock);
+ s->refcount++;
+ up_write(&slub_lock);
+ }Why do you need to increase the refcount? You made a full copy right?