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Date: Tue, 4 Feb 2014 16:13:26 +0100
From: Michal Hocko <mhocko@...e.cz>
To: Vladimir Davydov <vdavydov@...allels.com>
Cc: akpm@...ux-foundation.org, rientjes@...gle.com, penberg@...nel.org,
cl@...ux.com, glommer@...il.com, linux-mm@...ck.org,
linux-kernel@...r.kernel.org, devel@...nvz.org
Subject: Re: [PATCH 2/8] memcg, slab: remove cgroup name from memcg cache
names
On Tue 04-02-14 19:11:24, Vladimir Davydov wrote:
> 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@...allels.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.
OK, I am already switched to v2 (you are too fast...). I've just noticed
that this version has generated quite some discussion so I felt I should
react here first.
>
> 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
> >>
>
--
Michal Hocko
SUSE Labs
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