Re: [PATCH 05/16] slab: remove cachep in struct slab_rcu

From: JoonSoo Kim
Date: Fri Aug 23 2013 - 10:24:51 EST


2013/8/23 Christoph Lameter <cl@xxxxxxxxx>:
> On Fri, 23 Aug 2013, Joonsoo Kim wrote:
>
>> On Thu, Aug 22, 2013 at 05:53:00PM +0000, Christoph Lameter wrote:
>> > On Thu, 22 Aug 2013, Joonsoo Kim wrote:
>> >
>> > > We can get cachep using page in struct slab_rcu, so remove it.
>> >
>> > Ok but this means that we need to touch struct page. Additional cacheline
>> > in cache footprint.
>>
>> In following patch, we overload RCU_HEAD to LRU of struct page and
>> also overload struct slab to struct page. So there is no
>> additional cacheline footprint at final stage.
>
> If you do not use rcu (standard case) then you have an additional
> cacheline.
>

I don't get it. This patch only affect to the rcu case, because it
change the code
which is in kmem_rcu_free(). It doesn't touch anything in standard case.

Thanks.
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