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

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

On Thu, 27 Mar 2008 15:23:57 +0530
Balbir Singh <balbir@linux.vnet.ibm.com> wrote:
> >>>          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 see.

> 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
> 
I'll do something against "1" if I can think of.
I'd like to try "2" after this patches. Maybe reducing lock-bouncing can be
good help...

Thanks,
-Kame

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