Re: memo: mem+swap controller

[Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>]

On Fri, 01 Aug 2008 08:58:07 +0530, Balbir Singh <balbir@linux.vnet.ibm.com> wrote:
> Daisuke Nishimura wrote:
> > Hi, Kamezawa-san.
> > 
> > On Thu, 31 Jul 2008 10:15:33 +0900, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> >> Hi, mem+swap controller is suggested by Hugh Dickins and I think it's a great
> >> idea. Its concept is having 2 limits. (please point out if I misunderstand.)
> >>
> >>  - memory.limit_in_bytes       .... limit memory usage.
> >>  - memory.total_limit_in_bytes .... limit memory+swap usage.
> >>
> > When I've considered more, I wonder how we can accomplish
> > "do not use swap in this group".
> > 
> 
> It's easy use the memrlimit controller and set virtual address limit <=
> memory.limit_in_bytes. I use that to make sure I never swap out.
> 
I don't think it works under memory pressure *outside* of the group,
that is, global memory reclaim.
(I think "limit_in_bytes == total_limit_in_bytes" also works *inside* memory 
pressure.)

> > Setting "limit_in_bytes == total_limit_in_bytes" doesn't meet it, I think.
> > "limit_in_bytes = total_limit_in_bytes = 1G" cannot
> > avoid "memory.usage = 700M swap.usage = 300M" under memory pressure
> > outside of the group(and I think this behavior is the diffrence
> > of "memory controller + swap controller" and "mem+swap controller").
> > 
> > I think total_limit_in_bytes and swappiness(or some flag to indicate
> > "do not swap out"?) for each group would make more sense.
> 
> I do intend to add the swappiness feature soon for control groups.
> 
How does it work?
Does it affect global page reclaim?


Thanks,
Daisuke Nishimura.

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