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Re: [PATCH v3 15/16] memcg/sl[au]b: shrink dead caches [message #48040 is a reply to message #47913]

Fri, 21 September 2012 04:48

JoonSoo Kim
Messages: 9
Registered: September 2012

Junior Member

Hi Glauber.

2012/9/18 Glauber Costa <glommer@parallels.com>:
> diff --git a/mm/slub.c b/mm/slub.c
> index 0b68d15..9d79216 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -2602,6 +2602,7 @@ redo:
> } else
> __slab_free(s, page, x, addr);
>
> + kmem_cache_verify_dead(s);
> }

As far as u know, I am not a expert and don't know anything about memcg.
IMHO, this implementation may hurt system performance in some case.

In case of memcg is destoried, remained kmem_cache is marked "dead".
After it is marked,
every free operation to this "dead" kmem_cache call
kmem_cache_verify_dead() and finally call kmem_cache_shrink().
kmem_cache_shrink() do invoking kmalloc and flush_all() and taking a
lock for online node and invoking kfree.
Especially, flush_all() may hurt performance largely, because it call
has_cpu_slab() against all the cpus.

And I know some other case it can hurt system performance.
But, I don't mention it, because above case is sufficient to worry.

And, I found one case that destroying memcg's kmem_cache don't works properly.
If we destroy memcg after all object is freed, current implementation
doesn't destroy kmem_cache.
kmem_cache_destroy_work_func() check "cachep->memcg_params.nr_pages == 0",
but in this case, it return false, because kmem_cache may have
cpu_slab, and cpu_partials_slabs.
As we already free all objects, kmem_cache_verify_dead() is not invoked forever.
I think that we need another kmem_cache_shrink() in
kmem_cache_destroy_work_func().

I don't convince that I am right, so think carefully my humble opinion.

Thanks.

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[Message index]

		[PATCH v3 00/16] slab accounting for memcg By: Glauber Costa on Tue, 18 September 2012 14:11
		[PATCH v3 02/16] slub: use free_page instead of put_page for freeing kmalloc allocation By: Glauber Costa on Tue, 18 September 2012 14:11
		[PATCH v3 01/16] slab/slub: struct memcg_params By: Glauber Costa on Tue, 18 September 2012 14:11
		[PATCH v3 03/16] slab: Ignore the cflgs bit in cache creation By: Glauber Costa on Tue, 18 September 2012 14:11
		Re: [PATCH v3 03/16] slab: Ignore the cflgs bit in cache creation By: Christoph Lameter on Tue, 18 September 2012 15:20
		Re: [PATCH v3 03/16] slab: Ignore the cflgs bit in cache creation By: Tejun Heo on Fri, 21 September 2012 17:33
		[PATCH v3 09/16] sl[au]b: always get the cache from its page in kfree By: Glauber Costa on Tue, 18 September 2012 14:12
		Re: [PATCH v3 09/16] sl[au]b: always get the cache from its page in kfree By: Christoph Lameter on Tue, 18 September 2012 15:28
		Re: [PATCH v3 09/16] sl[au]b: always get the cache from its page in kfree By: Glauber Costa on Wed, 19 September 2012 07:42
		Re: [PATCH v3 09/16] sl[au]b: always get the cache from its page in kfree By: Christoph Lameter on Wed, 19 September 2012 14:14
		Re: [PATCH v3 09/16] sl[au]b: always get the cache from its page in kfree By: Pekka Enberg on Fri, 21 September 2012 09:33
		Re: [PATCH v3 09/16] sl[au]b: always get the cache from its page in kfree By: Glauber Costa on Fri, 21 September 2012 09:30
		Re: [PATCH v3 09/16] sl[au]b: always get the cache from its page in kfree By: Pekka Enberg on Fri, 21 September 2012 09:41
		Re: [PATCH v3 09/16] sl[au]b: always get the cache from its page in kfree By: Tejun Heo on Fri, 21 September 2012 20:07
		Re: [PATCH v3 09/16] sl[au]b: always get the cache from its page in kfree By: Pekka Enberg on Fri, 21 September 2012 20:14
		Re: [PATCH v3 09/16] sl[au]b: always get the cache from its page in kfree By: Tejun Heo on Fri, 21 September 2012 20:16
		[PATCH v3 06/16] memcg: infrastructure to match an allocation to the right cache By: Glauber Costa on Tue, 18 September 2012 14:12
		Re: [PATCH v3 06/16] memcg: infrastructure to match an allocation to the right cache By: Tejun Heo on Fri, 21 September 2012 18:32
		Re: [PATCH v3 06/16] memcg: infrastructure to match an allocation to the right cache By: Glauber Costa on Mon, 24 September 2012 08:46
		Re: [PATCH v3 06/16] memcg: infrastructure to match an allocation to the right cache By: Tejun Heo on Mon, 24 September 2012 17:56
		Re: [PATCH v3 06/16] memcg: infrastructure to match an allocation to the right cache By: Glauber Costa on Tue, 25 September 2012 13:57
		Re: [PATCH v3 06/16] memcg: infrastructure to match an allocation to the right cache By: Christoph Lameter on Tue, 25 September 2012 16:28
		Re: [PATCH v3 06/16] memcg: infrastructure to match an allocation to the right cache By: Tejun Heo on Fri, 21 September 2012 20:52
		Re: [PATCH v3 06/16] memcg: infrastructure to match an allocation to the right cache By: Glauber Costa on Mon, 24 September 2012 08:17
		Re: [PATCH v3 06/16] memcg: infrastructure to match an allocation to the right cache By: Tejun Heo on Mon, 24 September 2012 17:58
		[PATCH v3 04/16] provide a common place for initcall processing in kmem_cache By: Glauber Costa on Tue, 18 September 2012 14:11
		Re: [PATCH v3 04/16] provide a common place for initcall processing in kmem_cache By: Christoph Lameter on Tue, 18 September 2012 15:22
		[PATCH v3 07/16] memcg: skip memcg kmem allocations in specified code regions By: Glauber Costa on Tue, 18 September 2012 14:12
		Re: [PATCH v3 07/16] memcg: skip memcg kmem allocations in specified code regions By: Tejun Heo on Fri, 21 September 2012 19:59
		Re: [PATCH v3 07/16] memcg: skip memcg kmem allocations in specified code regions By: Glauber Costa on Mon, 24 September 2012 09:09
		Re: [PATCH v3 07/16] memcg: skip memcg kmem allocations in specified code regions By: Tejun Heo on Mon, 24 September 2012 17:47
		[PATCH v3 12/16] memcg/sl[au]b Track all the memcg children of a kmem_cache. By: Glauber Costa on Tue, 18 September 2012 14:12
		Re: [PATCH v3 12/16] memcg/sl[au]b Track all the memcg children of a kmem_cache. By: Tejun Heo on Fri, 21 September 2012 20:31
		[PATCH v3 14/16] slub: slub-specific propagation changes. By: Glauber Costa on Tue, 18 September 2012 14:12
		[PATCH v3 16/16] Add documentation about the kmem controller By: Glauber Costa on Tue, 18 September 2012 14:12
		[PATCH v3 08/16] slab: allow enable_cpu_cache to use preset values for its tunables By: Glauber Costa on Tue, 18 September 2012 14:12
		Re: [PATCH v3 08/16] slab: allow enable_cpu_cache to use preset values for its tunables By: Christoph Lameter on Tue, 18 September 2012 15:25
		Re: [PATCH v3 08/16] slab: allow enable_cpu_cache to use preset values for its tunables By: Glauber Costa on Wed, 19 September 2012 07:44
		Re: [PATCH v3 08/16] slab: allow enable_cpu_cache to use preset values for its tunables By: Pekka Enberg on Fri, 21 September 2012 09:29
		[PATCH v3 10/16] sl[au]b: Allocate objects from memcg cache By: Glauber Costa on Tue, 18 September 2012 14:12
		[PATCH v3 13/16] slab: slab-specific propagation changes. By: Glauber Costa on Tue, 18 September 2012 14:12
		Re: [PATCH v3 13/16] slab: slab-specific propagation changes. By: Christoph Lameter on Tue, 18 September 2012 17:00
		Re: [PATCH v3 13/16] slab: slab-specific propagation changes. By: Glauber Costa on Wed, 19 September 2012 07:41
		[PATCH v3 05/16] consider a memcg parameter in kmem_create_cache By: Glauber Costa on Tue, 18 September 2012 14:11
		Re: [PATCH v3 05/16] consider a memcg parameter in kmem_create_cache By: Tejun Heo on Fri, 21 September 2012 18:14
		Re: [PATCH v3 05/16] consider a memcg parameter in kmem_create_cache By: Glauber Costa on Mon, 24 September 2012 08:12
		Re: [PATCH v3 05/16] consider a memcg parameter in kmem_create_cache By: christoph on Mon, 24 September 2012 12:41
		Re: [PATCH v3 05/16] consider a memcg parameter in kmem_create_cache By: Glauber Costa on Mon, 24 September 2012 12:41
		Re: [PATCH v3 05/16] consider a memcg parameter in kmem_create_cache By: Christoph Lameter on Mon, 24 September 2012 13:42
		Re: [PATCH v3 05/16] consider a memcg parameter in kmem_create_cache By: Glauber Costa on Mon, 24 September 2012 13:44
		Re: [PATCH v3 05/16] consider a memcg parameter in kmem_create_cache By: Christoph Lameter on Mon, 24 September 2012 13:56
		Re: [PATCH v3 05/16] consider a memcg parameter in kmem_create_cache By: Glauber Costa on Mon, 24 September 2012 13:57
		Re: [PATCH v3 05/16] consider a memcg parameter in kmem_create_cache By: Pekka Enberg on Mon, 24 September 2012 15:38
		Re: [PATCH v3 05/16] consider a memcg parameter in kmem_create_cache By: Glauber Costa on Mon, 24 September 2012 15:36
		Re: [PATCH v3 05/16] consider a memcg parameter in kmem_create_cache By: Christoph Lameter on Mon, 24 September 2012 17:38
		Re: [PATCH v3 05/16] consider a memcg parameter in kmem_create_cache By: Christoph Lameter on Mon, 24 September 2012 17:39
		Re: [PATCH v3 05/16] consider a memcg parameter in kmem_create_cache By: Michal Hocko on Tue, 02 October 2012 14:46
		[PATCH v3 15/16] memcg/sl[au]b: shrink dead caches By: Glauber Costa on Tue, 18 September 2012 14:12
		Re: [PATCH v3 15/16] memcg/sl[au]b: shrink dead caches By: Christoph Lameter on Tue, 18 September 2012 17:02
		Re: [PATCH v3 15/16] memcg/sl[au]b: shrink dead caches By: Glauber Costa on Wed, 19 September 2012 07:40
		Re: [PATCH v3 15/16] memcg/sl[au]b: shrink dead caches By: Glauber Costa on Fri, 21 September 2012 08:40
		Re: [PATCH v3 15/16] memcg/sl[au]b: shrink dead caches By: JoonSoo Kim on Fri, 21 September 2012 09:28
		Re: [PATCH v3 15/16] memcg/sl[au]b: shrink dead caches By: Glauber Costa on Fri, 21 September 2012 09:31
		Re: [PATCH v3 15/16] memcg/sl[au]b: shrink dead caches By: Tejun Heo on Fri, 21 September 2012 20:40
		Re: [PATCH v3 15/16] memcg/sl[au]b: shrink dead caches By: Glauber Costa on Mon, 24 September 2012 08:25
		Re: [PATCH v3 15/16] memcg/sl[au]b: shrink dead caches By: Tejun Heo on Mon, 24 September 2012 17:43
		Re: [PATCH v3 15/16] memcg/sl[au]b: shrink dead caches By: JoonSoo Kim on Fri, 21 September 2012 04:48
		[PATCH v3 11/16] memcg: destroy memcg caches By: Glauber Costa on Tue, 18 September 2012 14:12
		Re: [PATCH v3 11/16] memcg: destroy memcg caches By: Tejun Heo on Fri, 21 September 2012 20:22
		Re: [PATCH v3 00/16] slab accounting for memcg By: Pekka Enberg on Fri, 21 September 2012 09:40
		Re: [PATCH v3 00/16] slab accounting for memcg By: Glauber Costa on Fri, 21 September 2012 09:43
		Re: [PATCH v3 00/16] slab accounting for memcg By: Tejun Heo on Fri, 21 September 2012 20:46
		Re: [PATCH v3 00/16] slab accounting for memcg By: Tejun Heo on Fri, 21 September 2012 20:47
		Re: [PATCH v3 00/16] slab accounting for memcg By: Glauber Costa on Mon, 24 September 2012 08:15

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