user_ns: improve the user_ns on-the-slab packaging
Currently on 64-bit arch the user_namespace is 2096 and when being
kmalloc-ed it resides on a 4k slab wasting 2003 bytes.
If we allocate a separate cache for it and reduce the hash size from 128
to 64 chains the packaging becomes *much* better - the struct is 1072
bytes and the hole between is 98 bytes.
[akpm@linux-foundation.org: s/__initcall/module_init/]
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Serge E. Hallyn <serge@hallyn.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 2591583..9da289c 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -12,6 +12,8 @@
#include <linux/highuid.h>
#include <linux/cred.h>
+static struct kmem_cache *user_ns_cachep __read_mostly;
+
/*
* Create a new user namespace, deriving the creator from the user in the
* passed credentials, and replacing that user with the new root user for the
@@ -26,7 +28,7 @@
struct user_struct *root_user;
int n;
- ns = kmalloc(sizeof(struct user_namespace), GFP_KERNEL);
+ ns = kmem_cache_alloc(user_ns_cachep, GFP_KERNEL);
if (!ns)
return -ENOMEM;
@@ -38,7 +40,7 @@
/* Alloc new root user. */
root_user = alloc_uid(ns, 0);
if (!root_user) {
- kfree(ns);
+ kmem_cache_free(user_ns_cachep, ns);
return -ENOMEM;
}
@@ -71,7 +73,7 @@
struct user_namespace *ns =
container_of(work, struct user_namespace, destroyer);
free_uid(ns->creator);
- kfree(ns);
+ kmem_cache_free(user_ns_cachep, ns);
}
void free_user_ns(struct kref *kref)
@@ -126,3 +128,10 @@
/* No useful relationship so no mapping */
return overflowgid;
}
+
+static __init int user_namespaces_init(void)
+{
+ user_ns_cachep = KMEM_CACHE(user_namespace, SLAB_PANIC);
+ return 0;
+}
+module_init(user_namespaces_init);