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Message-ID: <CALWz4izbTw4+7zbfiED9Lx=6RwiqxE11g5-fNRHTh=mcP=vQ2Q@mail.gmail.com>
Date: Tue, 10 Jan 2012 15:54:05 -0800
From: Ying Han <yinghan@...gle.com>
To: Johannes Weiner <hannes@...xchg.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Michal Hocko <mhocko@...e.cz>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
Balbir Singh <bsingharora@...il.com>, cgroups@...r.kernel.org,
linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [patch 1/2] mm: memcg: per-memcg reclaim statistics
Thank you for the patch and the stats looks reasonable to me, few
questions as below:
On Tue, Jan 10, 2012 at 7:02 AM, Johannes Weiner <hannes@...xchg.org> wrote:
> With the single per-zone LRU gone and global reclaim scanning
> individual memcgs, it's straight-forward to collect meaningful and
> accurate per-memcg reclaim statistics.
>
> This adds the following items to memory.stat:
Some of the previous discussions including patches have similar stats
in memory.vmscan_stat API, which collects all the per-memcg vmscan
stats. I would like to understand more why we add into memory.stat
instead, and do we have plan to keep extending memory.stat for those
vmstat like stats?
>
> pgreclaim
Not sure if we want to keep this more consistent to /proc/vmstat, then
it will be "pgsteal"?
> pgscan
>
> Number of pages reclaimed/scanned from that memcg due to its own
> hard limit (or physical limit in case of the root memcg) by the
> allocating task.
>
> kswapd_pgreclaim
> kswapd_pgscan
we have "pgscan_kswapd_*" in vmstat, so maybe ?
"pgsteal_kswapd"
"pgscan_kswapd"
>
> Reclaim activity from kswapd due to the memcg's own limit. Only
> applicable to the root memcg for now since kswapd is only triggered
> by physical limits, but kswapd-style reclaim based on memcg hard
> limits is being developped.
>
> hierarchy_pgreclaim
> hierarchy_pgscan
> hierarchy_kswapd_pgreclaim
> hierarchy_kswapd_pgscan
"pgsteal_hierarchy"
"pgsteal_kswapd_hierarchy"
..
No strong option on the naming, but try to make it more consistent to
existing API.
>
> Reclaim activity due to limitations in one of the memcg's parents.
>
> Signed-off-by: Johannes Weiner <hannes@...xchg.org>
> ---
> Documentation/cgroups/memory.txt | 4 ++
> include/linux/memcontrol.h | 10 +++++
> mm/memcontrol.c | 84 +++++++++++++++++++++++++++++++++++++-
> mm/vmscan.c | 7 +++
> 4 files changed, 103 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
> index cc0ebc5..eb9e982 100644
> --- a/Documentation/cgroups/memory.txt
> +++ b/Documentation/cgroups/memory.txt
> @@ -389,6 +389,10 @@ mapped_file - # of bytes of mapped file (includes tmpfs/shmem)
> pgpgin - # of pages paged in (equivalent to # of charging events).
> pgpgout - # of pages paged out (equivalent to # of uncharging events).
> swap - # of bytes of swap usage
> +pgreclaim - # of pages reclaimed due to this memcg's limit
> +pgscan - # of pages scanned due to this memcg's limit
> +kswapd_* - # reclaim activity by background daemon due to this memcg's limit
> +hierarchy_* - # reclaim activity due to pressure from parental memcg
> inactive_anon - # of bytes of anonymous memory and swap cache memory on
> LRU list.
> active_anon - # of bytes of anonymous and swap cache memory on active
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index bd3b102..6c1d69e 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -121,6 +121,8 @@ struct zone_reclaim_stat *mem_cgroup_get_reclaim_stat(struct mem_cgroup *memcg,
> struct zone *zone);
> struct zone_reclaim_stat*
> mem_cgroup_get_reclaim_stat_from_page(struct page *page);
> +void mem_cgroup_account_reclaim(struct mem_cgroup *, struct mem_cgroup *,
> + unsigned long, unsigned long, bool);
> extern void mem_cgroup_print_oom_info(struct mem_cgroup *memcg,
> struct task_struct *p);
> extern void mem_cgroup_replace_page_cache(struct page *oldpage,
> @@ -347,6 +349,14 @@ mem_cgroup_get_reclaim_stat_from_page(struct page *page)
> return NULL;
> }
>
> +static inline void mem_cgroup_account_reclaim(struct mem_cgroup *root,
> + struct mem_cgroup *memcg,
> + unsigned long nr_reclaimed,
> + unsigned long nr_scanned,
> + bool kswapd)
> +{
> +}
> +
> static inline void
> mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p)
> {
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 8e2a80d..170dff4 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -91,12 +91,23 @@ enum mem_cgroup_stat_index {
> MEM_CGROUP_STAT_NSTATS,
> };
>
> +#define MEM_CGROUP_EVENTS_KSWAPD 2
> +#define MEM_CGROUP_EVENTS_HIERARCHY 4
> +
> enum mem_cgroup_events_index {
> MEM_CGROUP_EVENTS_PGPGIN, /* # of pages paged in */
> MEM_CGROUP_EVENTS_PGPGOUT, /* # of pages paged out */
> MEM_CGROUP_EVENTS_COUNT, /* # of pages paged in/out */
> MEM_CGROUP_EVENTS_PGFAULT, /* # of page-faults */
> MEM_CGROUP_EVENTS_PGMAJFAULT, /* # of major page-faults */
> + MEM_CGROUP_EVENTS_PGRECLAIM,
> + MEM_CGROUP_EVENTS_PGSCAN,
> + MEM_CGROUP_EVENTS_KSWAPD_PGRECLAIM,
> + MEM_CGROUP_EVENTS_KSWAPD_PGSCAN,
> + MEM_CGROUP_EVENTS_HIERARCHY_PGRECLAIM,
> + MEM_CGROUP_EVENTS_HIERARCHY_PGSCAN,
> + MEM_CGROUP_EVENTS_HIERARCHY_KSWAPD_PGRECLAIM,
> + MEM_CGROUP_EVENTS_HIERARCHY_KSWAPD_PGSCAN,
missing comment here?
> MEM_CGROUP_EVENTS_NSTATS,
> };
> /*
> @@ -889,6 +900,38 @@ static inline bool mem_cgroup_is_root(struct mem_cgroup *memcg)
> return (memcg == root_mem_cgroup);
> }
>
> +/**
> + * mem_cgroup_account_reclaim - update per-memcg reclaim statistics
> + * @root: memcg that triggered reclaim
> + * @memcg: memcg that is actually being scanned
> + * @nr_reclaimed: number of pages reclaimed from @memcg
> + * @nr_scanned: number of pages scanned from @memcg
> + * @kswapd: whether reclaiming task is kswapd or allocator itself
> + */
> +void mem_cgroup_account_reclaim(struct mem_cgroup *root,
> + struct mem_cgroup *memcg,
> + unsigned long nr_reclaimed,
> + unsigned long nr_scanned,
> + bool kswapd)
> +{
> + unsigned int offset = 0;
> +
> + if (!root)
> + root = root_mem_cgroup;
> +
> + if (kswapd)
> + offset += MEM_CGROUP_EVENTS_KSWAPD;
> + if (root != memcg)
> + offset += MEM_CGROUP_EVENTS_HIERARCHY;
Just to be clear, here root cgroup has hierarchy_* stats always 0 ?
Also, we might want to consider renaming the root here, something like
target? The root is confusing with root_mem_cgroup.
--Ying
> +
> + preempt_disable();
> + __this_cpu_add(memcg->stat->events[MEM_CGROUP_EVENTS_PGRECLAIM + offset],
> + nr_reclaimed);
> + __this_cpu_add(memcg->stat->events[MEM_CGROUP_EVENTS_PGSCAN + offset],
> + nr_scanned);
> + preempt_enable();
> +}
> +
> void mem_cgroup_count_vm_event(struct mm_struct *mm, enum vm_event_item idx)
> {
> struct mem_cgroup *memcg;
> @@ -1662,6 +1705,8 @@ static int mem_cgroup_soft_reclaim(struct mem_cgroup *root_memcg,
> excess = res_counter_soft_limit_excess(&root_memcg->res) >> PAGE_SHIFT;
>
> while (1) {
> + unsigned long nr_reclaimed;
> +
> victim = mem_cgroup_iter(root_memcg, victim, &reclaim);
> if (!victim) {
> loop++;
> @@ -1687,8 +1732,11 @@ static int mem_cgroup_soft_reclaim(struct mem_cgroup *root_memcg,
> }
> if (!mem_cgroup_reclaimable(victim, false))
> continue;
> - total += mem_cgroup_shrink_node_zone(victim, gfp_mask, false,
> - zone, &nr_scanned);
> + nr_reclaimed = mem_cgroup_shrink_node_zone(victim, gfp_mask, false,
> + zone, &nr_scanned);
> + mem_cgroup_account_reclaim(root_mem_cgroup, victim, nr_reclaimed,
> + nr_scanned, current_is_kswapd());
> + total += nr_reclaimed;
> *total_scanned += nr_scanned;
> if (!res_counter_soft_limit_excess(&root_memcg->res))
> break;
> @@ -4023,6 +4071,14 @@ enum {
> MCS_SWAP,
> MCS_PGFAULT,
> MCS_PGMAJFAULT,
> + MCS_PGRECLAIM,
> + MCS_PGSCAN,
> + MCS_KSWAPD_PGRECLAIM,
> + MCS_KSWAPD_PGSCAN,
> + MCS_HIERARCHY_PGRECLAIM,
> + MCS_HIERARCHY_PGSCAN,
> + MCS_HIERARCHY_KSWAPD_PGRECLAIM,
> + MCS_HIERARCHY_KSWAPD_PGSCAN,
> MCS_INACTIVE_ANON,
> MCS_ACTIVE_ANON,
> MCS_INACTIVE_FILE,
> @@ -4047,6 +4103,14 @@ struct {
> {"swap", "total_swap"},
> {"pgfault", "total_pgfault"},
> {"pgmajfault", "total_pgmajfault"},
> + {"pgreclaim", "total_pgreclaim"},
> + {"pgscan", "total_pgscan"},
> + {"kswapd_pgreclaim", "total_kswapd_pgreclaim"},
> + {"kswapd_pgscan", "total_kswapd_pgscan"},
> + {"hierarchy_pgreclaim", "total_hierarchy_pgreclaim"},
> + {"hierarchy_pgscan", "total_hierarchy_pgscan"},
> + {"hierarchy_kswapd_pgreclaim", "total_hierarchy_kswapd_pgreclaim"},
> + {"hierarchy_kswapd_pgscan", "total_hierarchy_kswapd_pgscan"},
> {"inactive_anon", "total_inactive_anon"},
> {"active_anon", "total_active_anon"},
> {"inactive_file", "total_inactive_file"},
> @@ -4079,6 +4143,22 @@ mem_cgroup_get_local_stat(struct mem_cgroup *memcg, struct mcs_total_stat *s)
> s->stat[MCS_PGFAULT] += val;
> val = mem_cgroup_read_events(memcg, MEM_CGROUP_EVENTS_PGMAJFAULT);
> s->stat[MCS_PGMAJFAULT] += val;
> + val = mem_cgroup_read_events(memcg, MEM_CGROUP_EVENTS_PGRECLAIM);
> + s->stat[MCS_PGRECLAIM] += val;
> + val = mem_cgroup_read_events(memcg, MEM_CGROUP_EVENTS_PGSCAN);
> + s->stat[MCS_PGSCAN] += val;
> + val = mem_cgroup_read_events(memcg, MEM_CGROUP_EVENTS_KSWAPD_PGRECLAIM);
> + s->stat[MCS_KSWAPD_PGRECLAIM] += val;
> + val = mem_cgroup_read_events(memcg, MEM_CGROUP_EVENTS_KSWAPD_PGSCAN);
> + s->stat[MCS_KSWAPD_PGSCAN] += val;
> + val = mem_cgroup_read_events(memcg, MEM_CGROUP_EVENTS_HIERARCHY_PGRECLAIM);
> + s->stat[MCS_HIERARCHY_PGRECLAIM] += val;
> + val = mem_cgroup_read_events(memcg, MEM_CGROUP_EVENTS_HIERARCHY_PGSCAN);
> + s->stat[MCS_HIERARCHY_PGSCAN] += val;
> + val = mem_cgroup_read_events(memcg, MEM_CGROUP_EVENTS_HIERARCHY_KSWAPD_PGRECLAIM);
> + s->stat[MCS_HIERARCHY_KSWAPD_PGRECLAIM] += val;
> + val = mem_cgroup_read_events(memcg, MEM_CGROUP_EVENTS_HIERARCHY_KSWAPD_PGSCAN);
> + s->stat[MCS_HIERARCHY_KSWAPD_PGSCAN] += val;
>
> /* per zone stat */
> val = mem_cgroup_nr_lru_pages(memcg, BIT(LRU_INACTIVE_ANON));
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index c631234..e3fd8a7 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -2115,12 +2115,19 @@ static void shrink_zone(int priority, struct zone *zone,
>
> memcg = mem_cgroup_iter(root, NULL, &reclaim);
> do {
> + unsigned long nr_reclaimed = sc->nr_reclaimed;
> + unsigned long nr_scanned = sc->nr_scanned;
> struct mem_cgroup_zone mz = {
> .mem_cgroup = memcg,
> .zone = zone,
> };
>
> shrink_mem_cgroup_zone(priority, &mz, sc);
> +
> + mem_cgroup_account_reclaim(root, memcg,
> + sc->nr_reclaimed - nr_reclaimed,
> + sc->nr_scanned - nr_scanned,
> + current_is_kswapd());
> /*
> * Limit reclaim has historically picked one memcg and
> * scanned it with decreasing priority levels until
> --
> 1.7.7.5
>
--
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