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Date: Mon, 25 Apr 2011 20:46:48 +0300
From: Pekka Enberg <penberg@...nel.org>
To: linux-kernel@...r.kernel.org
Cc: Pekka Enberg <penberg@...nel.org>,
Christoph Lameter <cl@...ux.com>,
David Rientjes <rientjes@...gle.com>,
Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [RFC/PATCH 2/2] slub: Don't share struct kmem_cache for shared caches
This patch changes the slab cache sharing in SLUB to only share 'struct
kmem_cpu_cache' which contains the actual list of slabs and object freelists.
We no longer share 'struct kmem_cache' between merged caches so /proc/slabinfo
statistics work as expected:
Before:
# cat /proc/slabinfo | wc -l
104
After:
# cat /proc/slabinfo | wc -l
185
Cc: Christoph Lameter <cl@...ux.com>
Cc: David Rientjes <rientjes@...gle.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Pekka Enberg <penberg@...nel.org>
---
mm/slub.c | 98 +++++++++++++++++++-----------------------------------------
1 files changed, 31 insertions(+), 67 deletions(-)
diff --git a/mm/slub.c b/mm/slub.c
index cb61024..3a8fbca 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2349,6 +2349,11 @@ init_kmem_cache_node(struct kmem_cache_node *n, struct kmem_cache *s)
#endif
}
+static inline void dup_kmem_cache_cpus(struct kmem_cache *src, struct kmem_cache *dst)
+{
+ dst->cpu_slab = src->cpu_slab;
+}
+
static inline int alloc_kmem_cache_cpus(struct kmem_cache *s)
{
BUILD_BUG_ON(PERCPU_DYNAMIC_EARLY_SIZE <
@@ -3441,26 +3446,41 @@ static struct kmem_cache *find_mergeable(size_t size,
struct kmem_cache *kmem_cache_create(const char *name, size_t size,
size_t align, unsigned long flags, void (*ctor)(void *))
{
- struct kmem_cache *s;
+ struct kmem_cache *s, *parent;
char *n;
if (WARN_ON(!name))
return NULL;
down_write(&slub_lock);
- s = find_mergeable(size, align, flags, name, ctor);
- if (s) {
- s->refcount++;
+ parent = find_mergeable(size, align, flags, name, ctor);
+ if (parent) {
+ n = kstrdup(name, GFP_KERNEL);
+ if (!n)
+ goto err;
+
+ s = kmalloc(kmem_size, GFP_KERNEL);
+ if (!s)
+ goto err_free;
+
+ if (!kmem_cache_open(s, n, size, align, flags, ctor))
+ goto err_free;
+
+ dup_kmem_cache_cpus(parent, s);
+
+ parent->refcount++;
/*
* Adjust the object sizes so that we clear
* the complete object on kzalloc.
*/
- s->objsize = max(s->objsize, (int)size);
- s->inuse = max_t(int, s->inuse, ALIGN(size, sizeof(void *)));
+ parent->objsize = max(parent->objsize, (int)size);
+ parent->inuse = max_t(int, parent->inuse, ALIGN(size, sizeof(void *)));
- if (sysfs_slab_alias(s, name)) {
- s->refcount--;
- goto err;
+ list_add(&s->list, &slab_caches);
+ if (sysfs_slab_add(s)) {
+ parent->refcount--;
+ list_del(&s->list);
+ goto err_free;
}
up_write(&slub_lock);
return s;
@@ -4670,68 +4690,17 @@ static const struct kset_uevent_ops slab_uevent_ops = {
static struct kset *slab_kset;
-#define ID_STR_LENGTH 64
-
-/* Create a unique string id for a slab cache:
- *
- * Format :[flags-]size
- */
-static char *create_unique_id(struct kmem_cache *s)
-{
- char *name = kmalloc(ID_STR_LENGTH, GFP_KERNEL);
- char *p = name;
-
- BUG_ON(!name);
-
- *p++ = ':';
- /*
- * First flags affecting slabcache operations. We will only
- * get here for aliasable slabs so we do not need to support
- * too many flags. The flags here must cover all flags that
- * are matched during merging to guarantee that the id is
- * unique.
- */
- if (s->flags & SLAB_CACHE_DMA)
- *p++ = 'd';
- if (s->flags & SLAB_RECLAIM_ACCOUNT)
- *p++ = 'a';
- if (s->flags & SLAB_DEBUG_FREE)
- *p++ = 'F';
- if (!(s->flags & SLAB_NOTRACK))
- *p++ = 't';
- if (p != name + 1)
- *p++ = '-';
- p += sprintf(p, "%07d", s->size);
- BUG_ON(p > name + ID_STR_LENGTH - 1);
- return name;
-}
-
static int sysfs_slab_add(struct kmem_cache *s)
{
int err;
const char *name;
- int unmergeable;
if (slab_state < SYSFS)
/* Defer until later */
return 0;
- unmergeable = slab_unmergeable(s);
- if (unmergeable) {
- /*
- * Slabcache can never be merged so we can use the name proper.
- * This is typically the case for debug situations. In that
- * case we can catch duplicate names easily.
- */
- sysfs_remove_link(&slab_kset->kobj, s->name);
- name = s->name;
- } else {
- /*
- * Create a unique name for the slab as a target
- * for the symlinks.
- */
- name = create_unique_id(s);
- }
+ sysfs_remove_link(&slab_kset->kobj, s->name);
+ name = s->name;
s->kobj.kset = slab_kset;
err = kobject_init_and_add(&s->kobj, &slab_ktype, NULL, name);
@@ -4747,11 +4716,6 @@ static int sysfs_slab_add(struct kmem_cache *s)
return err;
}
kobject_uevent(&s->kobj, KOBJ_ADD);
- if (!unmergeable) {
- /* Setup first alias */
- sysfs_slab_alias(s, s->name);
- kfree(name);
- }
return 0;
}
--
1.7.0.4
--
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