[PATCH v9 09/13] memcg: create support routines for writeback

[KAMEZAWA Hiroyuki]

On Wed, 17 Aug 2011 09:15:01 -0700
Greg Thelen <gthelen at google.com> wrote:

> Introduce memcg routines to assist in per-memcg writeback:
> 
> - mem_cgroups_over_bground_dirty_thresh() determines if any cgroups need
>   writeback because they are over their dirty memory threshold.
> 
> - should_writeback_mem_cgroup_inode() will be called by writeback to
>   determine if a particular inode should be written back.  The answer
>   depends on the writeback context (foreground, background,
>   try_to_free_pages, etc.).
> 
> - mem_cgroup_writeback_done() is used periodically during writeback to
>   update memcg writeback data.
> 
> These routines make use of a new over_bground_dirty_thresh bitmap that
> indicates which mem_cgroup are over their respective dirty background
> threshold.  As this bitmap is indexed by css_id, the largest possible
> css_id value is needed to create the bitmap.  So move the definition of
> CSS_ID_MAX from cgroup.c to cgroup.h.  This allows users of css_id() to
> know the largest possible css_id value.  This knowledge can be used to
> build such per-cgroup bitmaps.
> 
> Make determine_dirtyable_memory() non-static because it is needed by
> mem_cgroup_writeback_done().
> 
> Signed-off-by: Greg Thelen <gthelen at google.com>

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