Re: [PATCH 7/8] memcg: don't use css_id any more

Michal Hocko
2013-04-08T15:01:50Z

On Mon 08-04-13 16:23:16, Li Zefan wrote:
> Now memcg uses cgroup->id instead of css_id. Update some comments and
> set mem_cgroup_subsys->use_id to 0.
>
> Signed-off-by: Li Zefan <lizefan@huawei.com>

Acked-by: Michal Hocko <mhocko@suse.cz>

> ---
> mm/memcontrol.c | 21 +++++++--------------
> 1 file changed, 7 insertions(+), 14 deletions(-)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 947dff1..26ee672 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -574,16 +574,11 @@ static void disarm_sock_keys(struct mem_cgroup *memcg)
> #ifdef CONFIG_MEMCG_KMEM
> /*
> * This will be the memcg's index in each cache's ->memcg_params->memcg_caches.
> - * There are two main reasons for not using the css_id for this:
> - * 1) this works better in sparse environments, where we have a lot of memcgs,
> - * but only a few kmem-limited. Or also, if we have, for instance, 200
> - * memcgs, and none but the 200th is kmem-limited, we'd have to have a
> - * 200 entry array for that.
> - *
> - * 2) In order not to violate the cgroup API, we would like to do all memory
> - * allocation in ->create(). At that point, we haven't yet allocated the
> - * css_id. Having a separate index prevents us from messing with the cgroup
> - * core for this
> + * The main reason for not using cgrp_id for this:
> + * this works better in sparse environments, where we have a lot of memcgs,
> + * but only a few kmem-limited. Or also, if we have, for instance, 200
> + * memcgs, and none but the 200th is kmem-limited, we'd have to have a
> + * 200 entry array for that.
> *
> * The current size of the caches array is stored in
> * memcg_limited_groups_array_size. It will double each time we have to
> @@ -598,10 +593,10 @@ int memcg_limited_groups_array_size;
> * cgroups is a reasonable guess. In the future, it could be a parameter or
> * tunable, but that is strictly not necessary.
> *
> - * MAX_SIZE should be as large as the number of css_ids. Ideally, we could get
> + * MAX_SIZE should be as large as the number of cgrp_ids. Ideally, we could get
> * this constant directly from cgroup, but it is understandable that this is
> * better kept as an internal representation in cgroup.c. In any case, the
> - * css_id space is not getting any smaller, and we don't have to necessarily
> + * cgrp_id space is not getting any smaller, and we don't have to necessarily
> * increase ours as well if it increases.
> */
> #define MEMCG_CACHES_MIN_SIZE 4
> @@ -6065,7 +6060,6 @@ static void __mem_cgroup_free(struct mem_cgroup *memcg)
> size_t size = memcg_size();
>
> mem_cgroup_remove_from_trees(memcg);
> - free_css_id(&mem_cgroup_subsys, &memcg->css);
>
> for_each_node(node)
> free_mem_cgroup_per_zone_info(memcg, node);
> @@ -6846,7 +6840,6 @@ struct cgroup_subsys mem_cgroup_subsys = {
> .attach = mem_cgroup_move_task,
> .base_cftypes = mem_cgroup_files,
> .early_init = 0,
> - .use_id = 1,
> };
>
> #ifdef CONFIG_MEMCG_SWAP
> --
> 1.8.0.2
>

--
Michal Hocko
SUSE Labs