Re: [RFC][PATCH 4/7][memcg] memcg use ID in page_cgroup

[KAMEZAWA Hiroyuki]

On Wed, 28 Jul 2010 12:18:20 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote:
 
> > > Hmm, but page-allocation-time doesn't sound very good for me.
> > > 
> > 
> > Why?
> > 
> 
> As you wrote, by attaching ID when a page cache is added, we'll have
> much chances of free-rider until it's paged out. So, adding some
> reseting-owner point may be good. 
> 
> But considering real world usage, I may be wrong.
> There will not be much free rider in real world, especially at write().
> Then, page-allocation time may be good.
> 
> (Because database doesn't use page-cache, there will be no big random write
>  application.)
> 

Sorry, one more reason. memory cgroup has much complex code for supporting
move_account, re-attaching memory cgroup per pages.
So, if you take care of task-move-between-groups, blkio-ID may have
some problems if you only support allocation-time accounting.

Thanks,
-Kame


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