linux-kernel - Re: [PATCH v2 04/11] kmem accounting basic infrastructure

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Date:	Fri, 17 Aug 2012 11:38:34 +0900
From:	Kamezawa Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	Glauber Costa <glommer@...allels.com>
CC:	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	cgroups@...r.kernel.org, devel@...nvz.org,
	Michal Hocko <mhocko@...e.cz>,
	Johannes Weiner <hannes@...xchg.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Christoph Lameter <cl@...ux.com>,
	David Rientjes <rientjes@...gle.com>,
	Pekka Enberg <penberg@...nel.org>
Subject: Re: [PATCH v2 04/11] kmem accounting basic infrastructure

(2012/08/13 17:36), Glauber Costa wrote:
> On 08/10/2012 09:02 PM, Kamezawa Hiroyuki wrote:
>> (2012/08/09 22:01), Glauber Costa wrote:
>>> This patch adds the basic infrastructure for the accounting of the slab
>>> caches. To control that, the following files are created:
>>>
>>>    * memory.kmem.usage_in_bytes
>>>    * memory.kmem.limit_in_bytes
>>>    * memory.kmem.failcnt
>>>    * memory.kmem.max_usage_in_bytes
>>>
>>> They have the same meaning of their user memory counterparts. They
>>> reflect the state of the "kmem" res_counter.
>>>
>>> The code is not enabled until a limit is set. This can be tested by the
>>> flag "kmem_accounted". This means that after the patch is applied, no
>>> behavioral changes exists for whoever is still using memcg to control
>>> their memory usage.
>>>
>>> We always account to both user and kernel resource_counters. This
>>> effectively means that an independent kernel limit is in place when the
>>> limit is set to a lower value than the user memory. A equal or higher
>>> value means that the user limit will always hit first, meaning that kmem
>>> is effectively unlimited.
>>>
>>> People who want to track kernel memory but not limit it, can set this
>>> limit to a very high number (like RESOURCE_MAX - 1page - that no one
>>> will ever hit, or equal to the user memory)
>>>
>>> Signed-off-by: Glauber Costa <glommer@...allels.com>
>>> CC: Michal Hocko <mhocko@...e.cz>
>>> CC: Johannes Weiner <hannes@...xchg.org>
>>> Reviewed-by: Kamezawa Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
>>
>> Could you add  a patch for documentation of this new interface and a text
>> explaining the behavior of "kmem_accounting" ?
>>
>> Hm, my concern is the difference of behavior between user page accounting and
>> kmem accounting...but this is how tcp-accounting is working.
>>
>> Once you add Documentation, it's okay to add my Ack.
>>
> I plan to add documentation in a separate patch. Due to that, can I add
> your ack to this patch here?
> 
> Also, I find that the description text in patch0 grew to be quite
> informative and complete. I plan to add that to the documentation
> if that is ok with you
> 

Ack to this patch.

-Kame


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