[PATCH v9 05/13] memcg: add mem_cgroup_mark_inode_dirty()
kamezawa.hiroyu at jp.fujitsu.com
Wed Aug 17 17:51:26 PDT 2011
On Wed, 17 Aug 2011 09:14:57 -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
> 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
> 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>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu at jp.fujitsu.com>
> Changelog since v8:
> - Use I_MEMCG_SHARED when initializing i_memcg.
> - Use 'memcg' rather than 'mem' for local variables. This is consistent with
> other memory controller code.
> - The logic in mem_cgroup_update_page_stat() and mem_cgroup_move_account() which
> marks inodes I_MEMCG_SHARED is now part of this patch. This makes more sense
> because this is that patch that introduces that shared-inode concept.
yes, this makes the patch clearer.
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