Date: Thu, 6 Nov 2008 20:07:25 +0900
From: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: "linux-mm@kvack.org" <linux-mm@kvack.org>,
       "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
       "balbir@linux.vnet.ibm.com" <balbir@linux.vnet.ibm.com>,
       "menage@google.com" <menage@google.com>, nishimura@mxp.nes.nec.co.jp
Subject: Re: [RFC][PATCH 3/6] memcg : mem+swap controller kconfig
Message-Id: <20081106200725.961e8f8f.nishimura@mxp.nes.nec.co.jp>
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	<20081105172050.1b280c56.kamezawa.hiroyu@jp.fujitsu.com>
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On Wed, 5 Nov 2008 17:20:50 +0900, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> Experimental.
> 
> Config and control variable for mem+swap controller.
> 
> This patch adds CONFIG_CGROUP_MEM_RES_CTLR_SWAP
> (memory resource controller swap extension.)
> 
> For accounting swap, it's obvious that we have to use additional memory
> to remember "who uses swap". This adds more overhead.
> So, it's better to offer "choice" to users. This patch adds 2 choices.
> 
> This patch adds 2 parameters to enable swap extension or not.
>   - CONFIG
>   - boot option
> 
> Changelog: v1 -> v2
>  - fixed typo.
>  - make default value of "do_swap_account" to be 0 and turned on 1
>    later if configured.
> 
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> 
looks good to me.

	Reviewed-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>

> 
>  Documentation/kernel-parameters.txt |    3 +++
>  include/linux/memcontrol.h          |    3 +++
>  init/Kconfig                        |   17 +++++++++++++++++
>  mm/memcontrol.c                     |   32 ++++++++++++++++++++++++++++++++
>  4 files changed, 55 insertions(+)
> 
> Index: mmotm-2.6.28-rc2+/init/Kconfig
> ===================================================================
> --- mmotm-2.6.28-rc2+.orig/init/Kconfig
> +++ mmotm-2.6.28-rc2+/init/Kconfig
> @@ -428,6 +428,23 @@ config CGROUP_MEM_RES_CTLR
>  config MM_OWNER
>  	bool
>  
> +config CGROUP_MEM_RES_CTLR_SWAP
> +	bool "Memory Resource Controller Swap Extension(EXPERIMENTAL)"
> +	depends on CGROUP_MEM_RES_CTLR && SWAP && EXPERIMENTAL
> +	help
> +	  Add swap management feature to memory resource controller. When you
> +	  enable this, you can limit mem+swap usage per cgroup. In other words,
> +	  when you disable this, memory resource controller has no cares to
> +	  usage of swap...a process can exhaust all of the swap. This extension
> +	  is useful when you want to avoid exhaustion swap but this itself
> +	  adds more overheads and consumes memory for remembering information.
> +	  Especially if you use 32bit system or small memory system, please
> +	  be careful about enabling this. When memory resource controller
> +	  is disabled by boot option, this will be automatically disabled and
> +	  there will be no overhead from this. Even when you set this config=y,
> +	  if boot option "noswapaccount" is set, swap will not be accounted.
> +
> +
>  endmenu
>  
>  config SYSFS_DEPRECATED
> Index: mmotm-2.6.28-rc2+/mm/memcontrol.c
> ===================================================================
> --- mmotm-2.6.28-rc2+.orig/mm/memcontrol.c
> +++ mmotm-2.6.28-rc2+/mm/memcontrol.c
> @@ -41,6 +41,15 @@
>  struct cgroup_subsys mem_cgroup_subsys __read_mostly;
>  #define MEM_CGROUP_RECLAIM_RETRIES	5
>  
> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
> +/* Turned on only when memory cgroup is enabled && really_do_swap_account = 0 */
> +int do_swap_account __read_mostly;
> +static int really_do_swap_account __initdata = 1; /* for remember boot option*/
> +#else
> +#define do_swap_account		(0)
> +#endif
> +
> +
>  /*
>   * Statistics for memory cgroup.
>   */
> @@ -1370,6 +1379,18 @@ static void mem_cgroup_free(struct mem_c
>  }
>  
>  
> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
> +static void __init enable_swap_cgroup(void)
> +{
> +	if (!mem_cgroup_subsys.disabled && really_do_swap_account)
> +		do_swap_account = 1;
> +}
> +#else
> +static void __init enable_swap_cgroup(void)
> +{
> +}
> +#endif
> +
>  static struct cgroup_subsys_state *
>  mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
>  {
> @@ -1378,6 +1399,7 @@ mem_cgroup_create(struct cgroup_subsys *
>  
>  	if (unlikely((cont->parent) == NULL)) {
>  		mem = &init_mem_cgroup;
> +		enable_swap_cgroup();
>  	} else {
>  		mem = mem_cgroup_alloc();
>  		if (!mem)
> @@ -1461,3 +1483,13 @@ struct cgroup_subsys mem_cgroup_subsys =
>  	.attach = mem_cgroup_move_task,
>  	.early_init = 0,
>  };
> +
> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
> +
> +static int __init disable_swap_account(char *s)
> +{
> +	really_do_swap_account = 0;
> +	return 1;
> +}
> +__setup("noswapaccount", disable_swap_account);
> +#endif
> Index: mmotm-2.6.28-rc2+/Documentation/kernel-parameters.txt
> ===================================================================
> --- mmotm-2.6.28-rc2+.orig/Documentation/kernel-parameters.txt
> +++ mmotm-2.6.28-rc2+/Documentation/kernel-parameters.txt
> @@ -1543,6 +1543,9 @@ and is between 256 and 4096 characters. 
>  
>  	nosoftlockup	[KNL] Disable the soft-lockup detector.
>  
> +	noswapaccount	[KNL] Disable accounting of swap in memory resource
> +			controller. (See Documentation/controllers/memory.txt)
> +
>  	nosync		[HW,M68K] Disables sync negotiation for all devices.
>  
>  	notsc		[BUGS=X86-32] Disable Time Stamp Counter
> Index: mmotm-2.6.28-rc2+/include/linux/memcontrol.h
> ===================================================================
> --- mmotm-2.6.28-rc2+.orig/include/linux/memcontrol.h
> +++ mmotm-2.6.28-rc2+/include/linux/memcontrol.h
> @@ -77,6 +77,9 @@ extern void mem_cgroup_record_reclaim_pr
>  extern long mem_cgroup_calc_reclaim(struct mem_cgroup *mem, struct zone *zone,
>  					int priority, enum lru_list lru);
>  
> +#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
> +extern int do_swap_account;
> +#endif
>  
>  #else /* CONFIG_CGROUP_MEM_RES_CTLR */
>  struct mem_cgroup;
> 
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