memcg: Fix init/Kconfig documentation

memcg: Fix init/Kconfig documentation

[Balbir Singh]

From: Balbir Singh <balbir@linux.vnet.ibm.com>
Date: Tue, 21 Oct 2008 11:12:45 +0530
Subject: [PATCH] memcg: Update Kconfig to remove the struct page overhead statement.

The memory resource controller no longer has a struct page overhead
associated with it. The init/Kconfig help has been replaced with
something more suitable based on the current implementation.

Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
---
 init/Kconfig |   11 ++++-------
 1 files changed, 4 insertions(+), 7 deletions(-)

diff --git a/init/Kconfig b/init/Kconfig
index 113c74c..1847f87 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -404,13 +404,10 @@ config CGROUP_MEM_RES_CTLR
 	  Provides a memory resource controller that manages both page cache and
 	  RSS memory.
 
-	  Note that setting this option increases fixed memory overhead
-	  associated with each page of memory in the system by 4/8 bytes
-	  and also increases cache misses because struct page on many 64bit
-	  systems will not fit into a single cache line anymore.
-
-	  Only enable when you're ok with these trade offs and really
-	  sure you need the memory resource controller.
+	  The config option adds a small memory overhead proportional to the
+	  size of memory. The controller can be disabled at run time by
+	  using the cgroup_disable=memory option, at which point the overhead
+	  disappears.
 
 	  This config option also selects MM_OWNER config option, which
 	  could in turn add some fork/exit overhead.
-- 
1.5.6.3


        Balbir

Re: memcg: Fix init/Kconfig documentation

[KAMEZAWA Hiroyuki]

On Tue, 21 Oct 2008 11:21:18 +0530
Balbir Singh <balbir@linux.vnet.ibm.com> wrote:

> From: Balbir Singh <balbir@linux.vnet.ibm.com>
> Date: Tue, 21 Oct 2008 11:12:45 +0530
> Subject: [PATCH] memcg: Update Kconfig to remove the struct page overhead statement.
> 
> The memory resource controller no longer has a struct page overhead
> associated with it. The init/Kconfig help has been replaced with
> something more suitable based on the current implementation.
> 
Oh, this is my version..could you merge if this includes something good ?

==
Fixes menu help text for memcg-allocate-page-cgroup-at-boot.patch.


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

 init/Kconfig |   16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

Index: mmotm-2.6.27+/init/Kconfig
===================================================================
--- mmotm-2.6.27+.orig/init/Kconfig
+++ mmotm-2.6.27+/init/Kconfig
@@ -401,16 +401,20 @@ config CGROUP_MEM_RES_CTLR
 	depends on CGROUPS && RESOURCE_COUNTERS
 	select MM_OWNER
 	help
-	  Provides a memory resource controller that manages both page cache and
-	  RSS memory.
+	  Provides a memory resource controller that manages both anonymous
+	  memory and page cache. (See Documentation/controllers/memory.txt)
 
 	  Note that setting this option increases fixed memory overhead
-	  associated with each page of memory in the system by 4/8 bytes
-	  and also increases cache misses because struct page on many 64bit
-	  systems will not fit into a single cache line anymore.
+	  associated with each page of memory in the system. By this,
+	  20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
+	  usage tracking struct at boot. Total amount of this is printed out
+	  at boot.
 
 	  Only enable when you're ok with these trade offs and really
-	  sure you need the memory resource controller.
+	  sure you need the memory resource controller. Even when you enable
+	  this, you can set "cgroup_disable=memory" at your boot option to
+	  disable memory resource controller and you can avoid almost all bads.
+	  (and lost benefits of memory resource contoller)
 
 	  This config option also selects MM_OWNER config option, which
 	  could in turn add some fork/exit overhead.

Re: memcg: Fix init/Kconfig documentation

[Balbir Singh]

KAMEZAWA Hiroyuki wrote:
> On Tue, 21 Oct 2008 11:21:18 +0530
> Balbir Singh <balbir@linux.vnet.ibm.com> wrote:
> 
>> From: Balbir Singh <balbir@linux.vnet.ibm.com>
>> Date: Tue, 21 Oct 2008 11:12:45 +0530
>> Subject: [PATCH] memcg: Update Kconfig to remove the struct page overhead statement.
>>
>> The memory resource controller no longer has a struct page overhead
>> associated with it. The init/Kconfig help has been replaced with
>> something more suitable based on the current implementation.
>>
> Oh, this is my version..could you merge if this includes something good ?
> 
> ==
> Fixes menu help text for memcg-allocate-page-cgroup-at-boot.patch.
> 
> 
> Signed-off-by: KAMEZAWA hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> 
>  init/Kconfig |   16 ++++++++++------
>  1 file changed, 10 insertions(+), 6 deletions(-)
> 
> Index: mmotm-2.6.27+/init/Kconfig
> ===================================================================
> --- mmotm-2.6.27+.orig/init/Kconfig
> +++ mmotm-2.6.27+/init/Kconfig
> @@ -401,16 +401,20 @@ config CGROUP_MEM_RES_CTLR
>  	depends on CGROUPS && RESOURCE_COUNTERS
>  	select MM_OWNER
>  	help
> -	  Provides a memory resource controller that manages both page cache and
> -	  RSS memory.
> +	  Provides a memory resource controller that manages both anonymous
> +	  memory and page cache. (See Documentation/controllers/memory.txt)
> 
>  	  Note that setting this option increases fixed memory overhead
> -	  associated with each page of memory in the system by 4/8 bytes
> -	  and also increases cache misses because struct page on many 64bit
> -	  systems will not fit into a single cache line anymore.
> +	  associated with each page of memory in the system. By this,
> +	  20(40)bytes/PAGE_SIZE on 32(64)bit system will be occupied by memory
> +	  usage tracking struct at boot. Total amount of this is printed out
> +	  at boot.
> 
>  	  Only enable when you're ok with these trade offs and really
> -	  sure you need the memory resource controller.
> +	  sure you need the memory resource controller. Even when you enable
> +	  this, you can set "cgroup_disable=memory" at your boot option to
> +	  disable memory resource controller and you can avoid almost all bads.
							       ^^^^ (replace)
							       the overhead

> +	  (and lost benefits of memory resource contoller)
               ^^^^
		lose

> 
>  	  This config option also selects MM_OWNER config option, which
>  	  could in turn add some fork/exit overhead.
> 

Looks good otherwise.

-- 
	Balbir