diff options
author | Vladimir Davydov <vdavydov@parallels.com> | 2015-02-12 14:59:20 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-02-12 18:54:09 -0800 |
commit | f7ce3190c4a35bf887adb7a1aa1ba899b679872d (patch) | |
tree | 8a40d93f1e796e1007d59e67541ce3044430b927 /include | |
parent | 49e7e7ff8d551b5b1e2f8da8497b9058cfa25672 (diff) | |
download | op-kernel-dev-f7ce3190c4a35bf887adb7a1aa1ba899b679872d.zip op-kernel-dev-f7ce3190c4a35bf887adb7a1aa1ba899b679872d.tar.gz |
slab: embed memcg_cache_params to kmem_cache
Currently, kmem_cache stores a pointer to struct memcg_cache_params
instead of embedding it. The rationale is to save memory when kmem
accounting is disabled. However, the memcg_cache_params has shrivelled
drastically since it was first introduced:
* Initially:
struct memcg_cache_params {
bool is_root_cache;
union {
struct kmem_cache *memcg_caches[0];
struct {
struct mem_cgroup *memcg;
struct list_head list;
struct kmem_cache *root_cache;
bool dead;
atomic_t nr_pages;
struct work_struct destroy;
};
};
};
* Now:
struct memcg_cache_params {
bool is_root_cache;
union {
struct {
struct rcu_head rcu_head;
struct kmem_cache *memcg_caches[0];
};
struct {
struct mem_cgroup *memcg;
struct kmem_cache *root_cache;
};
};
};
So the memory saving does not seem to be a clear win anymore.
OTOH, keeping a pointer to memcg_cache_params struct instead of embedding
it results in touching one more cache line on kmem alloc/free hot paths.
Besides, it makes linking kmem caches in a list chained by a field of
struct memcg_cache_params really painful due to a level of indirection,
while I want to make them linked in the following patch. That said, let
us embed it.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r-- | include/linux/slab.h | 17 | ||||
-rw-r--r-- | include/linux/slab_def.h | 2 | ||||
-rw-r--r-- | include/linux/slub_def.h | 2 |
3 files changed, 9 insertions, 12 deletions
diff --git a/include/linux/slab.h b/include/linux/slab.h index 2e3b448..1e03c11 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -473,14 +473,14 @@ static __always_inline void *kmalloc_node(size_t size, gfp_t flags, int node) #ifndef ARCH_SLAB_MINALIGN #define ARCH_SLAB_MINALIGN __alignof__(unsigned long long) #endif + +struct memcg_cache_array { + struct rcu_head rcu; + struct kmem_cache *entries[0]; +}; + /* * This is the main placeholder for memcg-related information in kmem caches. - * struct kmem_cache will hold a pointer to it, so the memory cost while - * disabled is 1 pointer. The runtime cost while enabled, gets bigger than it - * would otherwise be if that would be bundled in kmem_cache: we'll need an - * extra pointer chase. But the trade off clearly lays in favor of not - * penalizing non-users. - * * Both the root cache and the child caches will have it. For the root cache, * this will hold a dynamically allocated array large enough to hold * information about the currently limited memcgs in the system. To allow the @@ -495,10 +495,7 @@ static __always_inline void *kmalloc_node(size_t size, gfp_t flags, int node) struct memcg_cache_params { bool is_root_cache; union { - struct { - struct rcu_head rcu_head; - struct kmem_cache *memcg_caches[0]; - }; + struct memcg_cache_array __rcu *memcg_caches; struct { struct mem_cgroup *memcg; struct kmem_cache *root_cache; diff --git a/include/linux/slab_def.h b/include/linux/slab_def.h index b869d16..33d0490 100644 --- a/include/linux/slab_def.h +++ b/include/linux/slab_def.h @@ -70,7 +70,7 @@ struct kmem_cache { int obj_offset; #endif /* CONFIG_DEBUG_SLAB */ #ifdef CONFIG_MEMCG_KMEM - struct memcg_cache_params *memcg_params; + struct memcg_cache_params memcg_params; #endif struct kmem_cache_node *node[MAX_NUMNODES]; diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h index d82abd4..9abf04e 100644 --- a/include/linux/slub_def.h +++ b/include/linux/slub_def.h @@ -85,7 +85,7 @@ struct kmem_cache { struct kobject kobj; /* For sysfs */ #endif #ifdef CONFIG_MEMCG_KMEM - struct memcg_cache_params *memcg_params; + struct memcg_cache_params memcg_params; int max_attr_size; /* for propagation, maximum size of a stored attr */ #ifdef CONFIG_SYSFS struct kset *memcg_kset; |