Re: [PATCH 1/4] memcg, mm: introduce lowlimit reclaim

Michal Hocko
2014-05-06T19:58:13Z

Andrew, could you queue/fold this one, please?

On Fri 02-05-14 17:48:52, Michal Hocko wrote:
[...]
> From 3101ce41cc8c0c9691d98054e8811c66a77cd079 Mon Sep 17 00:00:00 2001
> From: Michal Hocko <mhocko@suse.cz>
> Date: Fri, 2 May 2014 17:47:32 +0200
> Subject: [PATCH] mmotm: memcg-mm-introduce-lowlimit-reclaim-fix.patch
>
> mem_cgroup_reclaim_eligible -> mem_cgroup_within_guarantee
> follow_low_limit -> honor_memcg_guarantee
> and as suggested by Johannes.
> ---
> include/linux/memcontrol.h | 6 +++---
> mm/memcontrol.c | 15 ++++++++-------
> mm/vmscan.c | 25 ++++++++++++++++---------
> 3 files changed, 27 insertions(+), 19 deletions(-)
>
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index 6c59056f4bc6..c00ccc5f70b9 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -92,7 +92,7 @@ bool __mem_cgroup_same_or_subtree(const struct mem_cgroup *root_memcg,
> bool task_in_mem_cgroup(struct task_struct *task,
> const struct mem_cgroup *memcg);
>
> -extern bool mem_cgroup_reclaim_eligible(struct mem_cgroup *memcg,
> +extern bool mem_cgroup_within_guarantee(struct mem_cgroup *memcg,
> struct mem_cgroup *root);
>
> extern struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page);
> @@ -291,10 +291,10 @@ static inline struct lruvec *mem_cgroup_page_lruvec(struct page *page,
> return &zone->lruvec;
> }
>
> -static inline bool mem_cgroup_reclaim_eligible(struct mem_cgroup *memcg,
> +static inline bool mem_cgroup_within_guarantee(struct mem_cgroup *memcg,
> struct mem_cgroup *root)
> {
> - return true;
> + return false;
> }
>
> static inline struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page)
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 7a276c0d141e..58982d18f6ea 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -2810,26 +2810,27 @@ static struct mem_cgroup *mem_cgroup_lookup(unsigned short id)
> }
>
> /**
> - * mem_cgroup_reclaim_eligible - checks whether given memcg is eligible for the
> - * reclaim
> + * mem_cgroup_within_guarantee - checks whether given memcg is within its
> + * memory guarantee
> * @memcg: target memcg for the reclaim
> * @root: root of the reclaim hierarchy (null for the global reclaim)
> *
> - * The given group is reclaimable if it is above its low limit and the same
> - * applies for all parents up the hierarchy until root (including).
> + * The given group is within its reclaim gurantee if it is below its low limit
> + * or the same applies for any parent up the hierarchy until root (including).
> + * Such a group might be excluded from the reclaim.
> */
> -bool mem_cgroup_reclaim_eligible(struct mem_cgroup *memcg,
> +bool mem_cgroup_within_guarantee(struct mem_cgroup *memcg,
> struct mem_cgroup *root)
> {
> do {
> if (!res_counter_low_limit_excess(&memcg->res))
> - return false;
> + return true;
> if (memcg == root)
> break;
>
> } while ((memcg = parent_mem_cgroup(memcg)));
>
> - return true;
> + return false;
> }
>
> struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page)
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 0f428158254e..5f923999bb79 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -2215,8 +2215,18 @@ static inline bool should_continue_reclaim(struct zone *zone,
> }
> }
>
> +/**
> + * __shrink_zone - shrinks a given zone
> + *
> + * @zone: zone to shrink
> + * @sc: scan control with additional reclaim parameters
> + * @honor_memcg_guarantee: do not reclaim memcgs which are within their memory
> + * guarantee
> + *
> + * Returns the number of reclaimed memcgs.
> + */
> static unsigned __shrink_zone(struct zone *zone, struct scan_control *sc,
> - bool follow_low_limit)
> + bool honor_memcg_guarantee)
> {
> unsigned long nr_reclaimed, nr_scanned;
> unsigned nr_scanned_groups = 0;
> @@ -2236,12 +2246,9 @@ static unsigned __shrink_zone(struct zone *zone, struct scan_control *sc,
> do {
> struct lruvec *lruvec;
>
> - /*
> - * Memcg might be under its low limit so we have to
> - * skip it during the first reclaim round
> - */
> - if (follow_low_limit &&
> - !mem_cgroup_reclaim_eligible(memcg, root)) {
> + /* Memcg might be protected from the reclaim */
> + if (honor_memcg_guarantee &&
> + mem_cgroup_within_guarantee(memcg, root)) {
> /*
> * It would be more optimal to skip the memcg
> * subtree now but we do not have a memcg iter
> @@ -2289,8 +2296,8 @@ static void shrink_zone(struct zone *zone, struct scan_control *sc)
> if (!__shrink_zone(zone, sc, true)) {
> /*
> * First round of reclaim didn't find anything to reclaim
> - * because of low limit protection so try again and ignore
> - * the low limit this time.
> + * because of the memory guantees for all memcgs in the
> + * reclaim target so try again and ignore guarantees this time.
> */
> __shrink_zone(zone, sc, false);
> }
> --
> 2.0.0.rc0
>
> --
> Michal Hocko
> SUSE Labs
>
> --
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--
Michal Hocko
SUSE Labs