[RFC][PATCH v7 03/14] memcg: add mem_cgroup_mark_inode_dirty()
KAMEZAWA Hiroyuki
kamezawa.hiroyu at jp.fujitsu.com
Fri May 13 02:31:34 PDT 2011
On Fri, 13 May 2011 01:47:42 -0700
Greg Thelen <gthelen at google.com> wrote:
> Create the mem_cgroup_mark_inode_dirty() routine, which is called when
> an inode is marked dirty. In kernels without memcg, this is an inline
> no-op.
>
> Add i_memcg field to struct address_space. When an inode is marked
> dirty with mem_cgroup_mark_inode_dirty(), the css_id of current memcg is
> recorded in i_memcg. Per-memcg writeback (introduced in a latter
> change) uses this field to isolate inodes associated with a particular
> memcg.
>
> The type of i_memcg is an 'unsigned short' because it stores the css_id
> of the memcg. Using a struct mem_cgroup pointer would be larger and
> also create a reference on the memcg which would hang memcg rmdir
> deletion. Usage of a css_id is not a reference so cgroup deletion is
> not affected. The memcg can be deleted without cleaning up the i_memcg
> field. When a memcg is deleted its pages are recharged to the cgroup
> parent, and the related inode(s) are marked as shared thus
> disassociating the inodes from the deleted cgroup.
>
> A mem_cgroup_mark_inode_dirty() tracepoint is also included to allow for
> easier understanding of memcg writeback operation.
>
> Signed-off-by: Greg Thelen <gthelen at google.com>
Seems simple and handy enough.
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu at jp.fujitsu.com>
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