On 03/12/2013 02:11 PM, Sha Zhengju wrote:
> Use jump label to patch the memcg page stat accounting code
> in or out when not used. when the first non-root memcg comes to
> life the code is patching in otherwise it is out.
>
> Signed-off-by: Sha Zhengju <handai.szj@xxxxxxxxxx>
> ---
> include/linux/memcontrol.h | 23 +++++++++++++++++++++++
> mm/memcontrol.c | 34 +++++++++++++++++++++++++++++++++-
> 2 files changed, 56 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index d6183f0..99dca91 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -42,6 +42,14 @@ struct mem_cgroup_reclaim_cookie {
> };
>
> #ifdef CONFIG_MEMCG
> +
> +extern struct static_key memcg_in_use_key;
> +
> +static inline bool mem_cgroup_in_use(void)
> +{
> + return static_key_false(&memcg_in_use_key);
> +}
> +
I believe the big advantage of the approach I've taken, including this
test in mem_cgroup_disabled(), is that we patch out a lot of things for
free.
We just need to be careful because some code expected that decision to
be permanent and now that status can change.
But I would still advocate for that.
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