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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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