Re: [PATCH v3 -mmotm 2/2] memcg: move charge of file pages

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

On Thu, 8 Apr 2010 14:11:31 +0900
Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> wrote:

> This patch adds support for moving charge of file pages, which include normal
> file, tmpfs file and swaps of tmpfs file. It's enabled by setting bit 1 of
> <target cgroup>/memory.move_charge_at_immigrate. Unlike the case of anonymous
> pages, file pages(and swaps) in the range mmapped by the task will be moved even
> if the task hasn't done page fault, i.e. they might not be the task's "RSS",
> but other task's "RSS" that maps the same file. And mapcount of the page is
> ignored(the page can be moved even if page_mapcount(page) > 1). So, conditions
> that the page/swap should be met to be moved is that it must be in the range
> mmapped by the target task and it must be charged to the old cgroup.
> 
> Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
> ---
>  Documentation/cgroups/memory.txt |   12 ++++++--
>  include/linux/swap.h             |    5 +++
>  mm/memcontrol.c                  |   55 +++++++++++++++++++++++++++++--------
>  mm/shmem.c                       |   37 +++++++++++++++++++++++++
>  4 files changed, 94 insertions(+), 15 deletions(-)
> 
> diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
> index 1b5bd04..13d40e7 100644
> --- a/Documentation/cgroups/memory.txt
> +++ b/Documentation/cgroups/memory.txt
> @@ -461,14 +461,20 @@ charges should be moved.
>     0  | A charge of an anonymous page(or swap of it) used by the target task.
>        | Those pages and swaps must be used only by the target task. You must
>        | enable Swap Extension(see 2.4) to enable move of swap charges.
> + -----+------------------------------------------------------------------------
> +   1  | A charge of file pages(normal file, tmpfs file(e.g. ipc shared memory)
> +      | and swaps of tmpfs file) mmaped by the target task. Unlike the case of
> +      | anonymous pages, file pages(and swaps) in the range mmapped by the task
> +      | will be moved even if the task hasn't done page fault, i.e. they might
> +      | not be the task's "RSS", but other task's "RSS" that maps the same file.
> +      | And mapcount of the page is ignored(the page can be moved even if
> +      | page_mapcount(page) > 1). You must enable Swap Extension(see 2.4) to
> +      | enable move of swap charges.
>  
>  Note: Those pages and swaps must be charged to the old cgroup.
> -Note: More type of pages(e.g. file cache, shmem,) will be supported by other
> -      bits in future.
>  

About both of documenataion for 0 and 1, I think following information is omitted.

 "An account of a page of task is moved only when it's under task's current memory cgroup."

Plz add somewhere easy-to-be-found.

But ok, the patch itself much simpler. Thank you for your patient works!

Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

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