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authorPavel Emelyanov <xemul@parallels.com>2011-01-12 17:00:46 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2011-01-13 08:03:18 -0800
commit6164281ab7a4d3bd42588d6b25984e960a2e032f (patch)
treeea4bf309efed7ec922431c6e5b5d659919eaf2ae /kernel
parente020e742e5dbd8c44d31706995dc13ddc732e274 (diff)
downloadlinux-linaro-precise-6164281ab7a4d3bd42588d6b25984e960a2e032f.tar.gz
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>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/user_namespace.c15
1 files changed, 12 insertions, 3 deletions
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 25915832291..9da289c34f2 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 @@ int create_user_ns(struct cred *new)
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 @@ int create_user_ns(struct cred *new)
/* 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 @@ static void free_user_ns_work(struct work_struct *work)
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 @@ gid_t user_ns_map_gid(struct user_namespace *to, const struct cred *cred, gid_t
/* 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);