[Devel] Re: [PATCH v5 11/18] sl[au]b: Allocate objects from memcg cache

[Glauber Costa]

On 10/29/2012 07:14 PM, JoonSoo Kim wrote:
> Hi, Glauber.
> 
> 2012/10/19 Glauber Costa <glommer at parallels.com>:
>> We are able to match a cache allocation to a particular memcg.  If the
>> task doesn't change groups during the allocation itself - a rare event,
>> this will give us a good picture about who is the first group to touch a
>> cache page.
>>
>> This patch uses the now available infrastructure by calling
>> memcg_kmem_get_cache() before all the cache allocations.
>>
>> Signed-off-by: Glauber Costa <glommer at parallels.com>
>> CC: Christoph Lameter <cl at linux.com>
>> CC: Pekka Enberg <penberg at cs.helsinki.fi>
>> CC: Michal Hocko <mhocko at suse.cz>
>> CC: Kamezawa Hiroyuki <kamezawa.hiroyu at jp.fujitsu.com>
>> CC: Johannes Weiner <hannes at cmpxchg.org>
>> CC: Suleiman Souhlal <suleiman at google.com>
>> CC: Tejun Heo <tj at kernel.org>
>> ---
>>  include/linux/slub_def.h | 15 ++++++++++-----
>>  mm/memcontrol.c          |  3 +++
>>  mm/slab.c                |  6 +++++-
>>  mm/slub.c                |  5 +++--
>>  4 files changed, 21 insertions(+), 8 deletions(-)
>>
>> diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
>> index 961e72e..ed330df 100644
>> --- a/include/linux/slub_def.h
>> +++ b/include/linux/slub_def.h
>> @@ -13,6 +13,8 @@
>>  #include <linux/kobject.h>
>>
>>  #include <linux/kmemleak.h>
>> +#include <linux/memcontrol.h>
>> +#include <linux/mm.h>
>>
>>  enum stat_item {
>>         ALLOC_FASTPATH,         /* Allocation from cpu slab */
>> @@ -209,14 +211,14 @@ static __always_inline int kmalloc_index(size_t size)
>>   * This ought to end up with a global pointer to the right cache
>>   * in kmalloc_caches.
>>   */
>> -static __always_inline struct kmem_cache *kmalloc_slab(size_t size)
>> +static __always_inline struct kmem_cache *kmalloc_slab(gfp_t flags, size_t size)
>>  {
>>         int index = kmalloc_index(size);
>>
>>         if (index == 0)
>>                 return NULL;
>>
>> -       return kmalloc_caches[index];
>> +       return memcg_kmem_get_cache(kmalloc_caches[index], flags);
>>  }
> 
> You don't need this,
> because memcg_kmem_get_cache() is invoked in both slab_alloc() and
> __cache_alloc_node().
> 
Indeed, I had noticed this already, and fixed myself - to be sent in the
next version I intend to get out in the open tonight or tomorrow.