[RFC][PATCH 9/11] memcg : mem+swap controlelr kconfig

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

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 extenstion or not.
  - CONFIG
  - boot option

This version uses policy of "default is enable if configured."
please tell me you dislike this. See patches following this in detail...

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>


 Documentation/kernel-parameters.txt |    3 +++
 include/linux/memcontrol.h          |    3 +++
 init/Kconfig                        |   16 ++++++++++++++++
 mm/memcontrol.c                     |   17 +++++++++++++++++
 4 files changed, 39 insertions(+)

Index: mmotm-2.6.27+/init/Kconfig
===================================================================
--- mmotm-2.6.27+.orig/init/Kconfig
+++ mmotm-2.6.27+/init/Kconfig
@@ -613,6 +613,22 @@ config KALLSYMS_EXTRA_PASS
 	   reported.  KALLSYMS_EXTRA_PASS is only a temporary workaround while
 	   you wait for kallsyms to be fixed.
 
+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 have no cares to
+	  usage of swap...a process can exhaust the all swap. This extension
+	  is useful when you want to avoid exhausion of 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 to enable this. When memory resource controller
+	  is disabled by boot option, this will be automatiaclly 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.
+
 
 config HOTPLUG
 	bool "Support for hot-pluggable devices" if EMBEDDED
Index: mmotm-2.6.27+/mm/memcontrol.c
===================================================================
--- mmotm-2.6.27+.orig/mm/memcontrol.c
+++ mmotm-2.6.27+/mm/memcontrol.c
@@ -41,6 +41,13 @@
 struct cgroup_subsys mem_cgroup_subsys __read_mostly;
 #define MEM_CGROUP_RECLAIM_RETRIES	5
 
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
+int do_swap_account __read_mostly = 1;
+#else
+#define do_swap_account		(0)
+#endif
+
+
 /*
  * Statistics for memory cgroup.
  */
@@ -1658,3 +1665,13 @@ 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)
+{
+	do_swap_account = 0;
+	return 1;
+}
+__setup("noswapaccount", disable_swap_account);
+#endif
Index: mmotm-2.6.27+/Documentation/kernel-parameters.txt
===================================================================
--- mmotm-2.6.27+.orig/Documentation/kernel-parameters.txt
+++ mmotm-2.6.27+/Documentation/kernel-parameters.txt
@@ -1540,6 +1540,9 @@ 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-2.6.27+/include/linux/memcontrol.h
===================================================================
--- mmotm-2.6.27+.orig/include/linux/memcontrol.h
+++ mmotm-2.6.27+/include/linux/memcontrol.h
@@ -80,6 +80,9 @@ 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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