Re: [PATCH v6 1/7] mm/memcg: scanning_global_lru means mem_cgroup_disabled

Michal Hocko
2012-03-26T15:04:34Z

[Adding Johannes to CC]

On Fri 23-03-12 01:56:16, Konstantin Khlebnikov wrote:
> From: Hugh Dickins <hughd@google.com>
>
> Although one has to admire the skill with which it has been concealed,
> scanning_global_lru(mz) is actually just an interesting way to test
> mem_cgroup_disabled(). Too many developer hours have been wasted on
> confusing it with global_reclaim(): just use mem_cgroup_disabled().

Is this really correct?

> Signed-off-by: Hugh Dickins <hughd@google.com>
> Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> Acked-by: Glauber Costa <glommer@parallels.com>
> ---
> mm/vmscan.c | 18 ++++--------------
> 1 files changed, 4 insertions(+), 14 deletions(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 49f15ef..c684f44 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
[...]
> @@ -1806,7 +1796,7 @@ static int inactive_anon_is_low(struct mem_cgroup_zone *mz)
> if (!total_swap_pages)
> return 0;
>
> - if (!scanning_global_lru(mz))
> + if (!mem_cgroup_disabled())
> return mem_cgroup_inactive_anon_is_low(mz->mem_cgroup,
> mz->zone);

mem_cgroup_inactive_anon_is_low calculation is slightly different than
what we have for cgroup_disabled case. calculate_zone_inactive_ratio
considers _all_ present pages in the zone while memcg variant only
active+inactive.

>
> @@ -1845,7 +1835,7 @@ static int inactive_file_is_low_global(struct zone *zone)
> */
> static int inactive_file_is_low(struct mem_cgroup_zone *mz)
> {
> - if (!scanning_global_lru(mz))
> + if (!mem_cgroup_disabled())
> return mem_cgroup_inactive_file_is_low(mz->mem_cgroup,
> mz->zone);
>
>
> --
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--
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9
Czech Republic