Date:	Tue, 16 Nov 2010 09:15:44 +0100
From:	Michal Hocko <mhocko@...e.cz>
To:	Daisuke Nishimura <nishimura@....nes.nec.co.jp>
Cc:	linux-mm@...ck.org,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	balbir@...ux.vnet.ibm.com
Subject: Re: [RFC PATCH] Make swap accounting default behavior configurable
 v3

On Tue 16-11-10 13:48:00, Daisuke Nishimura wrote:
> Acked-by: Daisuke Nishimura <nishimura@....nes.nec.co.jp>

Thank you. What should be next steps? Waiting for other ACKs or push it
through Andrew?
Btw. is this a stable tree material? I guess that distribution would
like to have this patch and the stable is the easiest way how to deliver
this.

> 
> Thank you for your work.
> Daisuke Nishimura.
> 
> On Mon, 15 Nov 2010 09:35:40 +0100
> Michal Hocko <mhocko@...e.cz> wrote:
> 
> > On Mon 15-11-10 10:13:35, Daisuke Nishimura wrote:
> > > On Fri, 12 Nov 2010 09:31:03 +0100
> > [...]
> > > > diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> > > > index ed45e98..7077148 100644
> > > > --- a/Documentation/kernel-parameters.txt
> > > > +++ b/Documentation/kernel-parameters.txt
> > > > @@ -1752,6 +1752,8 @@ and is between 256 and 4096 characters. It is defined in the file
> > > >  
> > > >  	noswapaccount	[KNL] Disable accounting of swap in memory resource
> > > >  			controller. (See Documentation/cgroups/memory.txt)
> > > > +	swapaccount	[KNL] Enable accounting of swap in memory resource
> > > > +			controller. (See Documentation/cgroups/memory.txt)
> > > >  
> > > >  	nosync		[HW,M68K] Disables sync negotiation for all devices.
> > > >  
> > > (I've add Andrew and Balbir to CC-list.)
> > > It seems that almost all parameters are listed in alphabetic order in the document,
> > > so I think it would be better to obey the rule.
> > 
> > You are right. The header of the file says:
> > 
> > " The following is a consolidated list of the kernel parameters as
> > implemented (mostly) by the __setup() macro and sorted into English
> > Dictionary order (defined as ignoring all punctuation and sorting digits
> > before letters in a case insensitive manner), and with descriptions
> > where known."
> > 
> > Updated patch follows bellow.
> > 
> > > 
> > > Thanks,
> > > Daisuke Nishimura.
> > 
> > Changes since v2:
> > * put the new parameter description to the proper (alphabetically sorted)
> >   place in Documentation/kernel-parameters.txt
> > 
> > Changes since v1:
> > * do not remove noswapaccount parameter and add swapaccount parameter instead
> > * Documentation/kernel-parameters.txt updated
> > ---
> > 
> > From 21df3801e2b65f47a2807534487ebb353dad6340 Mon Sep 17 00:00:00 2001
> > From: Michal Hocko <mhocko@...e.cz>
> > Date: Wed, 10 Nov 2010 13:30:04 +0100
> > Subject: [PATCH] Make swap accounting default behavior configurable
> > 
> > Swap accounting can be configured by CONFIG_CGROUP_MEM_RES_CTLR_SWAP
> > configuration option and then it is turned on by default. There is
> > a boot option (noswapaccount) which can disable this feature.
> > 
> > This makes it hard for distributors to enable the configuration option
> > as this feature leads to a bigger memory consumption and this is a no-go
> > for general purpose distribution kernel. On the other hand swap
> > accounting may be very usuful for some workloads.
> > 
> > This patch adds a new configuration option which controls the default
> > behavior (CGROUP_MEM_RES_CTLR_SWAP_ENABLED). If the option is selected
> > then the feature is turned on by default.
> > 
> > It also adds a new boot parameter swapaccount which (contrary to
> > noswapaccount) enables the feature. (I would consider swapaccount=yes|no
> > semantic with removed noswapaccount parameter much better but this
> > parameter is kind of API which might be in use and unexpected breakage
> > is no-go.)
> > 
> > The default behavior is unchanged (if CONFIG_CGROUP_MEM_RES_CTLR_SWAP is
> > enabled then CONFIG_CGROUP_MEM_RES_CTLR_SWAP_ENABLED is enabled as well)
> > 
> > Signed-off-by: Michal Hocko <mhocko@...e.cz>
> > ---
> >  Documentation/kernel-parameters.txt |    3 +++
> >  init/Kconfig                        |   13 +++++++++++++
> >  mm/memcontrol.c                     |   15 ++++++++++++++-
> >  3 files changed, 30 insertions(+), 1 deletions(-)
> > 
> > diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> > index ed45e98..14eafa5 100644
> > --- a/Documentation/kernel-parameters.txt
> > +++ b/Documentation/kernel-parameters.txt
> > @@ -2385,6 +2385,9 @@ and is between 256 and 4096 characters. It is defined in the file
> >  			improve throughput, but will also increase the
> >  			amount of memory reserved for use by the client.
> >  
> > +	swapaccount	[KNL] Enable accounting of swap in memory resource
> > +			controller. (See Documentation/cgroups/memory.txt)
> > +
> >  	swiotlb=	[IA-64] Number of I/O TLB slabs
> >  
> >  	switches=	[HW,M68k]
> > diff --git a/init/Kconfig b/init/Kconfig
> > index 88c1046..c972899 100644
> > --- a/init/Kconfig
> > +++ b/init/Kconfig
> > @@ -613,6 +613,19 @@ config CGROUP_MEM_RES_CTLR_SWAP
> >  	  if boot option "noswapaccount" is set, swap will not be accounted.
> >  	  Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
> >  	  size is 4096bytes, 512k per 1Gbytes of swap.
> > +config CGROUP_MEM_RES_CTLR_SWAP_ENABLED
> > +	bool "Memory Resource Controller Swap Extension enabled by default"
> > +	depends on CGROUP_MEM_RES_CTLR_SWAP
> > +	default y
> > +	help
> > +	  Memory Resource Controller Swap Extension comes with its price in
> > +	  a bigger memory consumption. General purpose distribution kernels
> > +	  which want to enable the feautre but keep it disabled by default
> > +	  and let the user enable it by swapaccount boot command line
> > +	  parameter should have this option unselected.
> > +	  For those who want to have the feature enabled by default should
> > +	  select this option (if, for some reason, they need to disable it
> > +	  then noswapaccount does the trick).
> >  
> >  menuconfig CGROUP_SCHED
> >  	bool "Group CPU scheduler"
> > diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> > index 9a99cfa..4f479fe 100644
> > --- a/mm/memcontrol.c
> > +++ b/mm/memcontrol.c
> > @@ -61,7 +61,14 @@ struct mem_cgroup *root_mem_cgroup __read_mostly;
> >  #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
> >  /* Turned on only when memory cgroup is enabled && really_do_swap_account = 1 */
> >  int do_swap_account __read_mostly;
> > -static int really_do_swap_account __initdata = 1; /* for remember boot option*/
> > +
> > +/* for remember boot option*/
> > +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP_ENABLED
> > +static int really_do_swap_account __initdata = 1;
> > +#else
> > +static int really_do_swap_account __initdata = 0;
> > +#endif
> > +
> >  #else
> >  #define do_swap_account		(0)
> >  #endif
> > @@ -4909,6 +4916,12 @@ struct cgroup_subsys mem_cgroup_subsys = {
> >  };
> >  
> >  #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
> > +static int __init enable_swap_account(char *s)
> > +{
> > +	really_do_swap_account = 1;
> > +	return 1;
> > +}
> > +__setup("swapaccount", enable_swap_account);
> >  
> >  static int __init disable_swap_account(char *s)
> >  {
> > -- 
> > 1.7.2.3
> > 
> > -- 
> > Michal Hocko
> > L3 team 
> > SUSE LINUX s.r.o.
> > Lihovarska 1060/12
> > 190 00 Praha 9    
> > Czech Republic
> 
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-- 
Michal Hocko
L3 team 
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9    
Czech Republic
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