Re: [PATCH v6 00/29] kmem controller for memcg.

JoonSoo Kim
2012-11-02T19:26:07Z

Hello, Glauber.

2012/11/2 Glauber Costa <glommer@parallels.com>:
> On 11/02/2012 04:04 AM, Andrew Morton wrote:
>> On Thu, 1 Nov 2012 16:07:16 +0400
>> Glauber Costa <glommer@parallels.com> wrote:
>>
>>> Hi,
>>>
>>> This work introduces the kernel memory controller for memcg. Unlike previous
>>> submissions, this includes the whole controller, comprised of slab and stack
>>> memory.
>>
>> I'm in the middle of (re)reading all this. Meanwhile I'll push it all
>> out to http://ozlabs.org/~akpm/mmots/ for the crazier testers.
>>
>> One thing:
>>
>>> Numbers can be found at https://lkml.org/lkml/2012/9/13/239
>>
>> You claim in the above that the fork worload is 'slab intensive". Or
>> at least, you seem to - it's a bit fuzzy.
>>
>> But how slab intensive is it, really?
>>
>> What is extremely slab intensive is networking. The networking guys
>> are very sensitive to slab performance. If this hasn't already been
>> done, could you please determine what impact this has upon networking?
>> I expect Eric Dumazet, Dave Miller and Tom Herbert could suggest
>> testing approaches.
>>
>
> I can test it, but unfortunately I am unlikely to get to prepare a good
> environment before Barcelona.
>
> I know, however, that Greg Thelen was testing netperf in his setup.
> Greg, do you have any publishable numbers you could share?

Below is my humble opinion.
I am worrying about data cache footprint which is possibly caused by
this patchset, especially slab implementation.
If there are several memcg cgroups, each cgroup has it's own kmem_caches.
When each group do slab-intensive job hard, data cache may be overflowed easily,
and cache miss rate will be high, therefore this would decrease system
performance highly.
Is there any result about this?

Thanks.