[PATCH 05/10] slab: allow enable_cpu_cache to use preset values for its tunables

Glauber Costa
2012-07-25T14:42:54Z

SLAB allows us to tune a particular cache behavior with tunables.
When creating a new memcg cache copy, we'd like to preserve any tunables
the parent cache already had.

This could be done by an explicit call to do_tune_cpucache() after the
cache is created. But this is not very convenient now that the caches are
created from common code, since this function is SLAB-specific.

Another method of doing that is taking advantage of the fact that
do_tune_cpucache() is always called from enable_cpucache(), which is
called at cache initialization. We can just preset the values, and
then things work as expected.

Signed-off-by: Glauber Costa <glommer@parallels.com>
CC: Christoph Lameter <cl@linux.com>
CC: Pekka Enberg <penberg@cs.helsinki.fi>
CC: Michal Hocko <mhocko@suse.cz>
CC: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
CC: Johannes Weiner <hannes@cmpxchg.org>
CC: Suleiman Souhlal <suleiman@google.com>
---
include/linux/slab.h | 3 ++-
mm/memcontrol.c | 2 +-
mm/slab.c | 19 ++++++++++++++++---
mm/slab_common.c | 7 ++++---
4 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/include/linux/slab.h b/include/linux/slab.h
index 9d3fd56..249a0d3 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -128,7 +128,7 @@ struct kmem_cache *kmem_cache_create(const char *, size_t, size_t,
void (*)(void *));
struct kmem_cache *
kmem_cache_create_memcg(struct mem_cgroup *, const char *, size_t, size_t,
- unsigned long, void (*)(void *));
+ unsigned long, void (*)(void *), struct kmem_cache *);
void kmem_cache_destroy(struct kmem_cache *);
int kmem_cache_shrink(struct kmem_cache *);
void kmem_cache_free(struct kmem_cache *, void *);
@@ -184,6 +184,7 @@ unsigned int kmem_cache_size(struct kmem_cache *);
#ifdef CONFIG_MEMCG_KMEM
struct mem_cgroup_cache_params {
struct mem_cgroup *memcg;
+ struct kmem_cache *parent;
int id;
};
#endif
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 854f6cc..b933474 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -585,7 +585,7 @@ static struct kmem_cache *kmem_cache_dup(struct mem_cgroup *memcg,
return NULL;

new = kmem_cache_create_memcg(memcg, name, s->object_size, s->align,
- (s->flags & ~SLAB_PANIC), s->ctor);
+ (s->flags & ~SLAB_PANIC), s->ctor, s);

kfree(name);
return new;
diff --git a/mm/slab.c b/mm/slab.c
index 7e7ec59..76bc98f 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3916,8 +3916,19 @@ static int do_tune_cpucache(struct kmem_cache *cachep, int limit,
static int enable_cpucache(struct kmem_cache *cachep, gfp_t gfp)
{
int err;
- int limit, shared;
-
+ int limit = 0;
+ int shared = 0;
+ int batchcount = 0;
+
+#ifdef CONFIG_MEMCG_KMEM
+ if (cachep->memcg_params.parent) {
+ limit = cachep->memcg_params.parent->limit;
+ shared = cachep->memcg_params.parent->shared;
+ batchcount = cachep->memcg_params.parent->batchcount;
+ }
+#endif
+ if (limit && shared && batchcount)
+ goto skip_setup;
/*
* The head array serves three purposes:
* - create a LIFO ordering, i.e. return objects that are cache-warm
@@ -3959,7 +3970,9 @@ static int enable_cpucache(struct kmem_cache *cachep, gfp_t gfp)
if (limit > 32)
limit = 32;
#endif
- err = do_tune_cpucache(cachep, limit, (limit + 1) / 2, shared, gfp);
+ batchcount = (limit + 1) / 2;
+skip_setup:
+ err = do_tune_cpucache(cachep, limit, batchcount, shared, gfp);
if (err)
printk(KERN_ERR "enable_cpucache failed for %s, error %d.\n",
cachep->name, -err);
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 1080ef2..562146b 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -80,7 +80,8 @@ unsigned long calculate_alignment(unsigned long flags,

struct kmem_cache *
kmem_cache_create_memcg(struct mem_cgroup *memcg, const char *name, size_t size,
- size_t align, unsigned long flags, void (*ctor)(void *))
+ size_t align, unsigned long flags, void (*ctor)(void *),
+ struct kmem_cache *parent_cache)
{
struct kmem_cache *s = NULL;
char *n;
@@ -149,9 +150,9 @@ kmem_cache_create_memcg(struct mem_cgroup *memcg, const char *name, size_t size,
s->ctor = ctor;
s->flags = flags;
s->align = calculate_alignment(flags, align, size);
-
#ifdef CONFIG_MEMCG_KMEM
s->memcg_params.memcg = memcg;
+ s->memcg_params.parent = parent_cache;
#endif

r = __kmem_cache_create(s);
@@ -184,7 +185,7 @@ out:
struct kmem_cache *kmem_cache_create(const char *name, size_t size, size_t align,
unsigned long flags, void (*ctor)(void *))
{
- return kmem_cache_create_memcg(NULL, name, size, align, flags, ctor);
+ return kmem_cache_create_memcg(NULL, name, size, align, flags, ctor, NULL);
}
EXPORT_SYMBOL(kmem_cache_create);

--
1.7.10.4