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    SubjectRe: [PATCH 1/7] cgroups: Shrink struct cgroup_subsys
    (Sorry for the delayed reply)

    Paul Menage wrote:
    > On Fri, Oct 22, 2010 at 1:09 AM, Li Zefan <lizf@cn.fujitsu.com> wrote:
    >> On x86_32, sizeof(struct cgroup_subsys) shrinks from 276 bytes
    >> to 264.
    >>
    >> Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
    >
    > Acked-by: Paul Menage <menage@google.com>
    >
    > Maybe use "bool" here?
    >

    Do you mean:

    bool active;
    bool disabled;
    ...

    ?

    With alignment 5-8 bool values == 8 bytes in 64-bit machine, compared to
    4 bytes with the approach this patch takes.

    > Paul
    >
    >> ---
    >> include/linux/cgroup.h | 10 ++++++----
    >> 1 files changed, 6 insertions(+), 4 deletions(-)
    >>
    >> diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
    >> index ed4ba11..e23ded6 100644
    >> --- a/include/linux/cgroup.h
    >> +++ b/include/linux/cgroup.h
    >> @@ -481,14 +481,16 @@ struct cgroup_subsys {
    >> void (*bind)(struct cgroup_subsys *ss, struct cgroup *root);
    >>
    >> int subsys_id;
    >> - int active;
    >> - int disabled;
    >> - int early_init;
    >> +
    >> + unsigned int active:1;
    >> + unsigned int disabled:1;
    >> + unsigned int early_init:1;
    >> /*
    >> * True if this subsys uses ID. ID is not available before cgroup_init()
    >> * (not available in early_init time.)
    >> */
    >> - bool use_id;
    >> + unsigned int use_id:1;
    >> +
    >> #define MAX_CGROUP_TYPE_NAMELEN 32
    >> const char *name;
    >>
    >> --
    >> 1.7.0.1
    >>
    >>


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