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

From: Michal Hocko
Date: Tue Feb 04 2014 - 09:45:38 EST


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@xxxxxxxxxxxxx>

I guess this one doesn't make much sense withou 1/8, right?

> ---
> 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
>

--
Michal Hocko
SUSE Labs
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/