Re: [PATCH -mmotm 5/8] memcg: improve performance in moving charge

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

On Mon, 21 Dec 2009 14:36:20 +0900
Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> wrote:

> This patch tries to reduce overheads in moving charge by:
> 
> - Instead of calling res_counter_uncharge() against the old cgroup in
>   __mem_cgroup_move_account() everytime, call res_counter_uncharge() at the end
>   of task migration once.
> - removed css_get(&to->css) from __mem_cgroup_move_account() because callers
>   should have already called css_get(). And removed css_put(&to->css) too,
>   which was called by callers of move_account on success of move_account.
> - Instead of calling __mem_cgroup_try_charge(), i.e. res_counter_charge(),
>   repeatedly, call res_counter_charge(PAGE_SIZE * count) in can_attach() if
>   possible.
> - Instead of calling css_get()/css_put() repeatedly, make use of coalesce
>   __css_get()/__css_put() if possible.
> 
> These changes reduces the overhead from 1.7sec to 0.6sec to move charges of 1G
> anonymous memory in my test environment.
> 
> Changelog: 2009/12/14
> - move cgroup part to another patch.
> - fix some bugs.
> 
> Changelog: 2009/12/04
> - new patch
> 
> Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

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