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SubjectRe: [RFC PATCH] Make swap accounting default behavior configurable v3
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@suse.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@suse.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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