linux-kernel - Re: [PATCH 2/2] slab: move kmem_cache

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Date:	Wed, 24 Oct 2012 14:03:50 +0400
From:	Glauber Costa <glommer@...allels.com>
To:	Pekka Enberg <penberg@...nel.org>
CC:	<linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
	Christoph Lameter <cl@...ux.com>,
	David Rientjes <rientjes@...gle.com>
Subject: Re: [PATCH 2/2] slab: move kmem_cache_free to common code

On 10/24/2012 12:56 PM, Pekka Enberg wrote:
> On Mon, Oct 22, 2012 at 5:05 PM, Glauber Costa <glommer@...allels.com> wrote:
>> +/**
>> + * kmem_cache_free - Deallocate an object
>> + * @cachep: The cache the allocation was from.
>> + * @objp: The previously allocated object.
>> + *
>> + * Free an object which was previously allocated from this
>> + * cache.
>> + */
>> +void kmem_cache_free(struct kmem_cache *s, void *x)
>> +{
>> +       __kmem_cache_free(s, x);
>> +       trace_kmem_cache_free(_RET_IP_, x);
>> +}
>> +EXPORT_SYMBOL(kmem_cache_free);
> 
> As Christoph mentioned, this is going to hurt performance. The proper
> way to do this is to implement the *hook* in mm/slab_common.c and call
> that from all the allocator specific kmem_cache_free() functions.
> 
>                         Pekka
> 
We would ideally like the hooks to be inlined as well. Specially for the
memcg-disabled case, this will only get us a function call for no reason.


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