[Devel] Re: [PATCH v5 06/14] memcg: kmem controller infrastructure

[Kamezawa Hiroyuki]

(2012/10/16 19:16), Glauber Costa wrote:
> This patch introduces infrastructure for tracking kernel memory pages to
> a given memcg. This will happen whenever the caller includes the flag
> __GFP_KMEMCG flag, and the task belong to a memcg other than the root.
> 
> In memcontrol.h those functions are wrapped in inline acessors.  The
> idea is to later on, patch those with static branches, so we don't incur
> any overhead when no mem cgroups with limited kmem are being used.
> 
> Users of this functionality shall interact with the memcg core code
> through the following functions:
> 
> memcg_kmem_newpage_charge: will return true if the group can handle the
>                             allocation. At this point, struct page is not
>                             yet allocated.
> 
> memcg_kmem_commit_charge: will either revert the charge, if struct page
>                            allocation failed, or embed memcg information
>                            into page_cgroup.
> 
> memcg_kmem_uncharge_page: called at free time, will revert the charge.
> 
> [ v2: improved comments and standardized function names ]
> [ v3: handle no longer opaque, functions not exported,
>    even more comments ]
> [ v4: reworked Used bit handling and surroundings for more clarity ]
> [ v5: simplified code for kmemcg compiled out and core functions in
>    memcontrol.c, moved kmem code to the middle to avoid forward decls ]
> 
> Signed-off-by: Glauber Costa <glommer at parallels.com>
> Acked-by: Michal Hocko <mhocko at suse.cz>
> CC: Christoph Lameter <cl at linux.com>
> CC: Pekka Enberg <penberg at cs.helsinki.fi>
> CC: Kamezawa Hiroyuki <kamezawa.hiroyu at jp.fujitsu.com>
> CC: Johannes Weiner <hannes at cmpxchg.org>
> CC: Tejun Heo <tj at kernel.org>

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