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Re: [PATCH v3 09/16] sl[au]b: always get the cache from its page in kfree [message #47970 is a reply to message #47969]

Fri, 21 September 2012 09:30

Glauber Costa
Messages: 916
Registered: October 2011

Senior Member

On 09/21/2012 01:33 PM, Pekka Enberg wrote:
> On Wed, Sep 19, 2012 at 10:42 AM, Glauber Costa <glommer@parallels.com> wrote:
>>>> index f2d760c..18de3f6 100644
>>>> --- a/mm/slab.c
>>>> +++ b/mm/slab.c
>>>> @@ -3938,9 +3938,12 @@ EXPORT_SYMBOL(__kmalloc);
>>>> * Free an object which was previously allocated from this
>>>> * cache.
>>>> */
>>>> -void kmem_cache_free(struct kmem_cache *cachep, void *objp)
>>>> +void kmem_cache_free(struct kmem_cache *s, void *objp)
>>>> {
>>>> unsigned long flags;
>>>> + struct kmem_cache *cachep = virt_to_cache(objp);
>>>> +
>>>> + VM_BUG_ON(!slab_equal_or_parent(cachep, s));
>>>
>>> This is an extremely hot path of the kernel and you are adding significant
>>> processing. Check how the benchmarks are influenced by this change.
>>> virt_to_cache can be a bit expensive.
>>
>> Would it be enough for you to have a separate code path for
>> !CONFIG_MEMCG_KMEM?
>>
>> I don't really see another way to do it, aside from deriving the cache
>> from the object in our case. I am open to suggestions if you do.
>
> We should assume that most distributions enable CONFIG_MEMCG_KMEM,
> right? Therfore, any performance impact should be dependent on whether
> or not kmem memcg is *enabled* at runtime or not.
>
> Can we use the "static key" thingy introduced by tracing folks for this?
>
Yes.

I am already using static keys extensively in this patchset, and that is
how I intend to handle this particular case.

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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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