Re: [RFC][PATCH 1/4] memcg: add softlimit interface and utilitiy function.

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

On Mon, 9 Mar 2009 14:24:23 +0530
Balbir Singh <balbir@linux.vnet.ibm.com> wrote:

> * KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> [2009-03-09 17:29:11]:
> 
> > On Mon, 9 Mar 2009 13:14:49 +0530
> > Balbir Singh <balbir@linux.vnet.ibm.com> wrote:
> > 
> > > * KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> [2009-03-09 16:39:07]:
> > > 
> > > > From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> > > > Adds an interface for defining sotlimit per memcg. (no handler in this patch.)
> > > > softlimit.priority and queue for softlimit is added in the next patch.
> > > > 
> > > > 
> > > > Changelog v1->v2:
> > > >  - For refactoring, divided a patch into 2 part and this patch just
> > > >    involves memory.softlimit interface.
> > > >  - Removed governor-detect routine, it was buggy in design.
> > > > 
> > > > Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> > > > ---
> > > >  mm/memcontrol.c |   62 ++++++++++++++++++++++++++++++++++++++++++++++++++++++--
> > > >  1 file changed, 60 insertions(+), 2 deletions(-)
> > > 
> > > 
> > > This patch breaks the semantics of resource counters. We would like to
> > > use resource counters to track all overhead. I've refined my tracking
> > > to an extent that the overhead does not show up at all, unless soft
> > > limits kick in. I oppose keeping soft limits outside of resource
> > > counters.
> > > 
> > 
> > BTW, any other user of res_counter than memcg in future ?
> 
> None so far.. but we once the core controllers are developed (CPU,
> memory), I would expect IO, tasks, number of open files, etc to be
> potential exploiters.
> 
> > I'm afraid that res_counter is decolated as chocolate-cake and will not taste
> > good for people who wants simple counter as simple pancake...
> > 
> 
> 
> I think keeping the design modular has helped. This way we can
> optimize resource counters without touching any controller. Only when
> features are enabled is when people get the chocolate cake feeling,
> not otherwise.
> 

Hmm, maybe reducing overhead as per-cpu counter etc.. is necessary anyway.


Thanks,
-Kame

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