Re: [PATCH 2/8] memcg, slab: remove cgroup name from memcg cache names

[Vladimir Davydov <vdavydov@parallels.com>]

On 02/04/2014 06:45 PM, Michal Hocko wrote:
> On Sun 02-02-14 20:33:47, Vladimir Davydov wrote:
>> The cgroup name is not informative at all in case the cgroup hierarchy
>> is not flat. Besides, we can always find the memcg a particular cache
>> belongs to by its kmemcg id, which is now exported via "memory.kmem.id"
>> cgroup fs file for each memcg.
>>
>> So let's remove the cgroup name part from kmem caches names - it will
>> greatly simplify the call paths and make the code look clearer.
>>
>> Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
> I guess this one doesn't make much sense withou 1/8, right?

Actually, the rest of the patchset does not depend on the logic of the
first two - they only have a couple of hunks overlapped. However, there
is v2 already.

Thanks.

>
>> ---
>>  mm/memcontrol.c  |   63 +++++++++++++-----------------------------------------
>>  mm/slab_common.c |    6 +++++-
>>  2 files changed, 20 insertions(+), 49 deletions(-)
>>
>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
>> index 91d242707404..3351c5b5486d 100644
>> --- a/mm/memcontrol.c
>> +++ b/mm/memcontrol.c
>> @@ -3405,44 +3405,6 @@ void mem_cgroup_destroy_cache(struct kmem_cache *cachep)
>>  	schedule_work(&cachep->memcg_params->destroy);
>>  }
>>  
>> -static struct kmem_cache *memcg_create_kmem_cache(struct mem_cgroup *memcg,
>> -						  struct kmem_cache *s)
>> -{
>> -	struct kmem_cache *new = NULL;
>> -	static char *tmp_name = NULL;
>> -	static DEFINE_MUTEX(mutex);	/* protects tmp_name */
>> -
>> -	BUG_ON(!memcg_can_account_kmem(memcg));
>> -
>> -	mutex_lock(&mutex);
>> -	/*
>> -	 * kmem_cache_create_memcg duplicates the given name and
>> -	 * cgroup_name for this name requires RCU context.
>> -	 * This static temporary buffer is used to prevent from
>> -	 * pointless shortliving allocation.
>> -	 */
>> -	if (!tmp_name) {
>> -		tmp_name = kmalloc(PATH_MAX, GFP_KERNEL);
>> -		if (!tmp_name)
>> -			goto out;
>> -	}
>> -
>> -	rcu_read_lock();
>> -	snprintf(tmp_name, PATH_MAX, "%s(%d:%s)", s->name,
>> -			 memcg_cache_id(memcg), cgroup_name(memcg->css.cgroup));
>> -	rcu_read_unlock();
>> -
>> -	new = kmem_cache_create_memcg(memcg, tmp_name, s->object_size, s->align,
>> -				      (s->flags & ~SLAB_PANIC), s->ctor, s);
>> -	if (new)
>> -		new->allocflags |= __GFP_KMEMCG;
>> -	else
>> -		new = s;
>> -out:
>> -	mutex_unlock(&mutex);
>> -	return new;
>> -}
>> -
>>  void kmem_cache_destroy_memcg_children(struct kmem_cache *s)
>>  {
>>  	struct kmem_cache *c;
>> @@ -3489,12 +3451,6 @@ void kmem_cache_destroy_memcg_children(struct kmem_cache *s)
>>  	mutex_unlock(&activate_kmem_mutex);
>>  }
>>  
>> -struct create_work {
>> -	struct mem_cgroup *memcg;
>> -	struct kmem_cache *cachep;
>> -	struct work_struct work;
>> -};
>> -
>>  static void mem_cgroup_destroy_all_caches(struct mem_cgroup *memcg)
>>  {
>>  	struct kmem_cache *cachep;
>> @@ -3512,13 +3468,24 @@ static void mem_cgroup_destroy_all_caches(struct mem_cgroup *memcg)
>>  	mutex_unlock(&memcg->slab_caches_mutex);
>>  }
>>  
>> +struct create_work {
>> +	struct mem_cgroup *memcg;
>> +	struct kmem_cache *cachep;
>> +	struct work_struct work;
>> +};
>> +
>>  static void memcg_create_cache_work_func(struct work_struct *w)
>>  {
>> -	struct create_work *cw;
>> +	struct create_work *cw = container_of(w, struct create_work, work);
>> +	struct mem_cgroup *memcg = cw->memcg;
>> +	struct kmem_cache *s = cw->cachep;
>> +	struct kmem_cache *new;
>>  
>> -	cw = container_of(w, struct create_work, work);
>> -	memcg_create_kmem_cache(cw->memcg, cw->cachep);
>> -	css_put(&cw->memcg->css);
>> +	new = kmem_cache_create_memcg(memcg, s->name, s->object_size, s->align,
>> +				      (s->flags & ~SLAB_PANIC), s->ctor, s);
>> +	if (new)
>> +		new->allocflags |= __GFP_KMEMCG;
>> +	css_put(&memcg->css);
>>  	kfree(cw);
>>  }
>>  
>> diff --git a/mm/slab_common.c b/mm/slab_common.c
>> index 1ec3c619ba04..152d9b118b7a 100644
>> --- a/mm/slab_common.c
>> +++ b/mm/slab_common.c
>> @@ -213,7 +213,11 @@ kmem_cache_create_memcg(struct mem_cgroup *memcg, const char *name, size_t size,
>>  	s->align = calculate_alignment(flags, align, size);
>>  	s->ctor = ctor;
>>  
>> -	s->name = kstrdup(name, GFP_KERNEL);
>> +	if (!memcg)
>> +		s->name = kstrdup(name, GFP_KERNEL);
>> +	else
>> +		s->name = kasprintf(GFP_KERNEL, "%s:%d",
>> +				    name, memcg_cache_id(memcg));
>>  	if (!s->name)
>>  		goto out_free_cache;
>>  
>> -- 
>> 1.7.10.4
>>

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