Re: [-mm] [PATCH 0/4] memcg : radix-tree page_cgroup v2

[Balbir Singh <balbir@linux.vnet.ibm.com>]

KAMEZAWA Hiroyuki wrote:
> On Thu, 27 Mar 2008 18:12:42 +0900
> KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote:
> 
>> Hi
>>
>>>          TEST                                BASELINE     RESULT      INDEX
>>> (1)      Execl Throughput                        43.0     2868.8      667.2
>>> (2)      Execl Throughput                        43.0     2810.3      653.6
>>> (3)      Execl Throughput                        43.0     2836.9      659.7
>>> (4)      Execl Throughput                        43.0     2846.0      661.9
>>> (5)      Execl Throughput                        43.0     2862.0      665.6
>>> (6)      Execl Throughput                        43.0     3110.0      723.3
>>>
>>> (1) .... rc5-mm1 + memory controller
>>> (2) .... patch 1/4 is applied.      (use radix-tree always.)
>>> (3) .... patch [1-3]/4 are applied. (caching by percpu)
>>> (4) .... patch [1-4]/4 are applied. (uses prefetch)
>>> (5) .... adjust sizeof(struct page) to be 64 bytes by padding.
>>> (6) .... rc5-mm1 *without* memory controller
>> I am very surprised this result. 
>> 723.3 -> 667.2 seems large performance impact.
>>
>> Why do you need count resource usage when unlimited limit.
>> Could you separate unlimited group to resource usage counting and no counting.
>> I hope default cgroup keep no counting and no decrease performance.
> 
> At first, I'd like to reduce this overhead even under memory resource
> controller's accounting ;)
> We have boot-time-disable option now. But it doesn't seem what you want.
> 
> Considering workaround....
> In current system, *unlimited* doesn't mean *no account*.
> So, I think we have an option to add "no account" flag per cgroup.
> 
> Hmm..some interface to do
> - allow "no account" -> "account"
> - disallow "account" -> "no account"
> 
> Balbir-san, how do you think ?

The reason we do accounting for default group is to allow reporting of
usage/statistics and in the future when we do hierarchial accounting and
control, it will be much more useful.

I like the interface idea, but I'd like to do two things

1. Keeping accounting on by default or have an option to do so
2. Reduce the memory controller overhead

-- 
	Warm Regards,
	Balbir Singh
	Linux Technology Center
	IBM, ISTL

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