cgroups: 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[=1|0] which enhances the
original noswapaccount parameter semantic by means of enable/disable logic
(defaults to 1 if no value is provided to be still consistent with
noswapaccount).
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>
Acked-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 92e83e5..cdd2a6e 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2385,6 +2385,11 @@
improve throughput, but will also increase the
amount of memory reserved for use by the client.
+ swapaccount[=0|1]
+ [KNL] Enable accounting of swap in memory resource
+ controller if no parameter or 1 is given or disable
+ it if 0 is given (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 @@
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 26218df..7a22b41 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -61,7 +61,14 @@
#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
@@ -4920,10 +4927,20 @@
};
#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
+static int __init enable_swap_account(char *s)
+{
+ /* consider enabled if no parameter or 1 is given */
+ if (!s || !strcmp(s, "1"))
+ really_do_swap_account = 1;
+ else if (!strcmp(s, "0"))
+ really_do_swap_account = 0;
+ return 1;
+}
+__setup("swapaccount", enable_swap_account);
static int __init disable_swap_account(char *s)
{
- really_do_swap_account = 0;
+ enable_swap_account("0");
return 1;
}
__setup("noswapaccount", disable_swap_account);
