Commit a42c390c authored by Michal Hocko's avatar Michal Hocko Committed by Linus Torvalds
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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

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: default avatarMichal Hocko <>
Acked-by: default avatarDaisuke Nishimura <>
Cc: Balbir Singh <>
Cc: KAMEZAWA Hiroyuki <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent b1dd693e
......@@ -2385,6 +2385,11 @@ 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.
[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]
......@@ -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.
bool "Memory Resource Controller Swap Extension enabled by default"
default y
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"
......@@ -61,7 +61,14 @@ struct mem_cgroup *root_mem_cgroup __read_mostly;
/* 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*/
static int really_do_swap_account __initdata = 1;
static int really_do_swap_account __initdata = 0;
#define do_swap_account (0)
......@@ -4920,10 +4927,20 @@ struct cgroup_subsys mem_cgroup_subsys = {
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;
return 1;
__setup("noswapaccount", disable_swap_account);
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