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Date: Fri, 24 Jun 2011 14:40:42 -0700
Message-ID: <BANLkTimBPo6PyMKB4_ASL2nP2xiajExFK7ZWwvCUkdaqssnHiQ@mail.gmail.com>
Subject: Re: [PATCH 3/7] memcg: add memory.scan_stat
From: Ying Han <yinghan@google.com>
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To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: "linux-mm@kvack.org" <linux-mm@kvack.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "akpm@linux-foundation.org" <akpm@linux-foundation.org>, "nishimura@mxp.nes.nec.co.jp" <nishimura@mxp.nes.nec.co.jp>, "bsingharora@gmail.com" <bsingharora@gmail.com>, Michal Hocko <mhocko@suse.cz>, "hannes@cmpxchg.org" <hannes@cmpxchg.org>

On Tue, Jun 21, 2011 at 5:20 PM, KAMEZAWA Hiroyuki
<kamezawa.hiroyu@jp.fujitsu.com> wrote:
> On Mon, 20 Jun 2011 23:49:54 -0700
> Ying Han <yinghan@google.com> wrote:
>
>> On Wed, Jun 15, 2011 at 8:53 PM, KAMEZAWA Hiroyuki <
>> kamezawa.hiroyu@jp.fujitsu.com> wrote:
>>
>> > From e08990dd9ada13cf236bec1ef44b207436434b8e Mon Sep 17 00:00:00 2001
>> > From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
>> > Date: Wed, 15 Jun 2011 14:11:01 +0900
>> > Subject: [PATCH 3/7] memcg: add memory.scan_stat
>> >
>> > commit log of commit 0ae5e89 " memcg: count the soft_limit reclaim in.=
.."
>> > says it adds scanning stats to memory.stat file. But it doesn't becaus=
e
>> > we considered we needed to make a concensus for such new APIs.
>> >
>> > This patch is a trial to add memory.scan_stat. This shows
>> > =A0- the number of scanned pages
>> > =A0- the number of recleimed pages
>> > =A0- the number of elaplsed time (including sleep/pause time)
>> > =A0for both of direct/soft reclaim and shrinking caused by changing li=
mit
>> > =A0or force_empty.
>> >
>> > The biggest difference with oringinal Ying's one is that this file
>> > can be reset by some write, as
>> >
>> > =A0# echo 0 ...../memory.scan_stat
>> >
>> > [kamezawa@bluextal ~]$ cat /cgroup/memory/A/memory.scan_stat
>> > scanned_pages_by_limit 358470
>> > freed_pages_by_limit 180795
>> > elapsed_ns_by_limit 21629927
>> > scanned_pages_by_system 0
>> > freed_pages_by_system 0
>> > elapsed_ns_by_system 0
>> > scanned_pages_by_shrink 76646
>> > freed_pages_by_shrink 38355
>> > elappsed_ns_by_shrink 31990670
>> >
>>
>> elapsed?
>>
>
> you'r right.
>
>>
>> > total_scanned_pages_by_limit 358470
>> > total_freed_pages_by_limit 180795
>> > total_elapsed_ns_by_hierarchical 216299275
>> > total_scanned_pages_by_system 0
>> > total_freed_pages_by_system 0
>> > total_elapsed_ns_by_system 0
>> > total_scanned_pages_by_shrink 76646
>> > total_freed_pages_by_shrink 38355
>> > total_elapsed_ns_by_shrink 31990670
>> >
>> > total_xxxx is for hierarchy management.
>> >
>>
>> For some reason, i feel the opposite where the local stat (like
>> "scanned_pages_by_limit") are reclaimed under hierarchical reclaim. The
>> total_xxx stats are only incremented for root_mem which is the cgroup
>> triggers the hierarchical reclaim. So:
>>
>> total_scanned_pages_by_limit: number of pages being scanned while the me=
mcg
>> hits its limit
>> scanned_pages_by_limit: number of pages being scanned while one of the
>> memcg's ancestor hits its limit
>>
>> am i missing something?
>>
>
> scanned_pages_by_limit: one of ancestors and itself's limit.

yes, and that is what I understood.
>
>
>
>
>>
>> >
>> > This will be useful for further memcg developments and need to be
>> > developped before we do some complicated rework on LRU/softlimit
>> > management.
>> >
>> > Now, scan/free/elapsed_by_system is incomplete but future works of
>> > Johannes at el. will fill remaining information and then, we can
>> > look into problems of isolation between memcgs.
>> >
>> > Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
>> > ---
>> > =A0Documentation/cgroups/memory.txt | =A0 33 +++++++++
>> > =A0include/linux/memcontrol.h =A0 =A0 =A0 | =A0 16 ++++
>> > =A0include/linux/swap.h =A0 =A0 =A0 =A0 =A0 =A0 | =A0 =A06 -
>> > =A0mm/memcontrol.c =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0| =A0135
>> > +++++++++++++++++++++++++++++++++++++--
>> > =A0mm/vmscan.c =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0| =A0 27 +++=
+++-
>> > =A05 files changed, 199 insertions(+), 18 deletions(-)
>> >
>> > Index: mmotm-0615/Documentation/cgroups/memory.txt
>> > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>> > --- mmotm-0615.orig/Documentation/cgroups/memory.txt
>> > +++ mmotm-0615/Documentation/cgroups/memory.txt
>> > @@ -380,7 +380,7 @@ will be charged as a new owner of it.
>> >
>> > =A05.2 stat file
>> >
>> > -memory.stat file includes following statistics
>> > +5.2.1 memory.stat file includes following statistics
>> >
>> > =A0# per-memory cgroup local status
>> > =A0cache =A0 =A0 =A0 =A0 =A0- # of bytes of page cache memory.
>> > @@ -438,6 +438,37 @@ Note:
>> > =A0 =A0 =A0 =A0 file_mapped is accounted only when the memory cgroup i=
s owner of
>> > page
>> > =A0 =A0 =A0 =A0 cache.)
>> >
>> > +5.2.2 memory.scan_stat
>> > +
>> > +memory.scan_stat includes statistics information for memory scanning =
and
>> > +freeing, reclaiming. The statistics shows memory scanning information
>> > since
>> > +memory cgroup creation and can be reset to 0 by writing 0 as
>> > +
>> > + #echo 0 > ../memory.scan_stat
>> > +
>> > +This file contains following statistics.
>> > +
>> > +scanned_pages_by_limit - # of scanned pages at hitting limit.
>> > +freed_pages_by_limit =A0 - # of freed pages at hitting limit.
>> > +elapsed_ns_by_limit =A0 =A0- nano sec of elappsed time at LRU scan at
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0h=
itting limit.(this includes sleep
>> > time.)
>> >
>> elapsed?
>>
>> > +
>> > +scanned_pages_by_system =A0 =A0 =A0 =A0- # of scanned pages by the ke=
rnel.
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 (Now, this value mea=
ns global memory reclaim
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 caused by system=
 memory shortage with a hint
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0of softlimit. "No=
 soft limit" case will be
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0supported in futu=
re.)
>> > +freed_pages_by_system =A0- # of freed pages by the kernel.
>> > +elapsed_ns_by_system =A0 - nano sec of elappsed time by kernel.
>> > +
>> > +scanned_pages_by_shrink =A0 =A0 =A0 =A0- # of scanned pages by shrink=
ing.
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 (i.e=
. changes of limit, force_empty,
>> > etc.)
>> > +freed_pages_by_shrink =A0- # of freed pages by shirkining.
>> > +elappsed_ns_by_shrink =A0- nano sec of elappsed time at shrinking.
>> >
>> elapsed?
>>
>> > +
>> > +total_xxx includes the statistics of children scanning caused by the
>> > cgroup.
>> >
>>
>> based on the code inspection, the total_xxx also includes the cgroup's s=
can
>> stat as well.
>>
>
> yes.
>
>
>> +
>> > +
>> > =A05.3 swappiness
>> >
>> > =A0Similar to /proc/sys/vm/swappiness, but affecting a hierarchy of gr=
oups
>> > only.
>> > Index: mmotm-0615/include/linux/memcontrol.h
>> > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>> > --- mmotm-0615.orig/include/linux/memcontrol.h
>> > +++ mmotm-0615/include/linux/memcontrol.h
>> > @@ -120,6 +120,22 @@ struct zone_reclaim_stat*
>> > =A0mem_cgroup_get_reclaim_stat_from_page(struct page *page);
>> > =A0extern void mem_cgroup_print_oom_info(struct mem_cgroup *memcg,
>> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 =A0struct task_struct *p);
>> > +struct memcg_scanrecord {
>> > + =A0 =A0 =A0 struct mem_cgroup *mem; /* scanend memory cgroup */
>> > + =A0 =A0 =A0 struct mem_cgroup *root; /* scan target hierarchy root *=
/
>> > + =A0 =A0 =A0 int context; =A0 =A0 =A0 =A0 =A0 =A0/* scanning context =
(see memcontrol.c) */
>> > + =A0 =A0 =A0 unsigned long nr_scanned; /* the number of scanned pages=
 */
>> > + =A0 =A0 =A0 unsigned long nr_freed; /* the number of freed pages */
>> > + =A0 =A0 =A0 unsigned long elappsed; /* nsec of time elapsed while sc=
anning */
>> >
>> elapsed?
>>
>> > +};
>> > +
>> > +extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *=
mem,
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 =A0 =A0 =A0 =A0 =A0 gfp_t gfp_mask, bool
>> > noswap,
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 =A0 =A0 =A0 =A0 =A0 struct memcg_scanrecord
>> > *rec);
>> > +extern unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *m=
em,
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 =A0 =A0 =A0 =A0 gfp_t gfp_mask, bool
>> > noswap,
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 =A0 =A0 =A0 =A0 struct zone *zone,
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 =A0 =A0 =A0 =A0 struct memcg_scanrecord
>> > *rec);
>> >
>> > =A0#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
>> > =A0extern int do_swap_account;
>> > Index: mmotm-0615/include/linux/swap.h
>> > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>> > --- mmotm-0615.orig/include/linux/swap.h
>> > +++ mmotm-0615/include/linux/swap.h
>> > @@ -253,12 +253,6 @@ static inline void lru_cache_add_file(st
>> > =A0/* linux/mm/vmscan.c */
>> > =A0extern unsigned long try_to_free_pages(struct zonelist *zonelist, i=
nt
>> > order,
>> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 =A0gfp_t gfp_mask, nodemask_t *mask);
>> > -extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *=
mem,
>> > - =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 =A0 =A0 =A0 =A0 =A0 gfp_t gfp_mask, bool
>> > noswap);
>> > -extern unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *m=
em,
>> > - =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 =A0 =A0 =A0 =A0 gfp_t gfp_mask, bool
>> > noswap,
>> > - =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 =A0 =A0 =A0 =A0 struct zone *zone,
>> > - =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 =A0 =A0 =A0 =A0 unsigned long *nr_scanned);
>> > =A0extern int __isolate_lru_page(struct page *page, int mode, int file=
);
>> > =A0extern unsigned long shrink_all_memory(unsigned long nr_pages);
>> > =A0extern int vm_swappiness;
>> > Index: mmotm-0615/mm/memcontrol.c
>> > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>> > --- mmotm-0615.orig/mm/memcontrol.c
>> > +++ mmotm-0615/mm/memcontrol.c
>> > @@ -203,6 +203,57 @@ struct mem_cgroup_eventfd_list {
>> > =A0static void mem_cgroup_threshold(struct mem_cgroup *mem);
>> > =A0static void mem_cgroup_oom_notify(struct mem_cgroup *mem);
>> >
>> > +enum {
>> > + =A0 =A0 =A0 SCAN_BY_LIMIT,
>> > + =A0 =A0 =A0 FREED_BY_LIMIT,
>> > + =A0 =A0 =A0 ELAPSED_BY_LIMIT,
>> > +
>> > + =A0 =A0 =A0 SCAN_BY_SYSTEM,
>> > + =A0 =A0 =A0 FREED_BY_SYSTEM,
>> > + =A0 =A0 =A0 ELAPSED_BY_SYSTEM,
>> > +
>> > + =A0 =A0 =A0 SCAN_BY_SHRINK,
>> > + =A0 =A0 =A0 FREED_BY_SHRINK,
>> > + =A0 =A0 =A0 ELAPSED_BY_SHRINK,
>> > + =A0 =A0 =A0 NR_SCANSTATS,
>> > +};
>> > +#define __FREED =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0(1)
>> > +#define =A0 =A0 =A0 =A0__ELAPSED =A0 =A0 =A0 (2)
>> >
>>
>> /tab/space/
>>
>>
>> > +
>> > +struct scanstat {
>> > + =A0 =A0 =A0 spinlock_t =A0 =A0 =A0lock;
>> > + =A0 =A0 =A0 unsigned long =A0 stats[NR_SCANSTATS]; =A0 =A0/* local s=
tatistics */
>> > + =A0 =A0 =A0 unsigned long =A0 totalstats[NR_SCANSTATS]; =A0 /* hiera=
rchical */
>> > +};

I wonder why not extending the mem_cgroup_stat_cpu struct, and then we
can use the per-cpu counters like others.

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index b7d2d79..5b8bbe9 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -138,6 +138,7 @@ struct mem_cgroup_stat_cpu {
        long count[MEM_CGROUP_STAT_NSTATS];
        unsigned long events[MEM_CGROUP_EVENTS_NSTATS];
        unsigned long targets[MEM_CGROUP_NTARGETS];
+       unsigned long reclaim_stats[MEMCG_RECLAIM_NSTATS];
 };

 /*
@@ -557,6 +558,101 @@ static void __mem_cgroup_target_update(struct
mem_cgroup *mem, int target)
        this_cpu_write(mem->stat->targets[target], next);
 }

+void mem_cgroup_update_reclaim_stat(struct mem_cgroup *mem,
+                                   enum mem_cgroup_reclaim_stat_index idx,
+                                   unsigned long num)
+{
+       this_cpu_add(mem->stat->reclaim_stats[idx], num);
+}


>> > +
>> > +const char *scanstat_string[NR_SCANSTATS] =3D {
>> > + =A0 =A0 =A0 "scanned_pages_by_limit",
>> > + =A0 =A0 =A0 "freed_pages_by_limit",
>> > + =A0 =A0 =A0 "elapsed_ns_by_limit",
>> > +
>> > + =A0 =A0 =A0 "scanned_pages_by_system",
>> > + =A0 =A0 =A0 "freed_pages_by_system",
>> > + =A0 =A0 =A0 "elapsed_ns_by_system",
>> > +
>> > + =A0 =A0 =A0 "scanned_pages_by_shrink",
>> > + =A0 =A0 =A0 "freed_pages_by_shrink",
>> > + =A0 =A0 =A0 "elappsed_ns_by_shrink",
>> >
>> elapsed?
>>
>> > +};
>> > +
>> > +const char *total_scanstat_string[NR_SCANSTATS] =3D {
>> > + =A0 =A0 =A0 "total_scanned_pages_by_limit",
>> > + =A0 =A0 =A0 "total_freed_pages_by_limit",
>> > + =A0 =A0 =A0 "total_elapsed_ns_by_hierarchical",
>> >
>>
>> typo?
>>
>>
>> > +
>> > + =A0 =A0 =A0 "total_scanned_pages_by_system",
>> > + =A0 =A0 =A0 "total_freed_pages_by_system",
>> > + =A0 =A0 =A0 "total_elapsed_ns_by_system",
>> > +
>> > + =A0 =A0 =A0 "total_scanned_pages_by_shrink",
>> > + =A0 =A0 =A0 "total_freed_pages_by_shrink",
>> > + =A0 =A0 =A0 "total_elapsed_ns_by_shrink",
>> > +};
>> > +
>> > =A0/*
>> > =A0* The memory controller data structure. The memory controller contr=
ols
>> > both
>> > =A0* page cache and RSS per cgroup. We would eventually like to provid=
e
>> > @@ -264,7 +315,8 @@ struct mem_cgroup {
>> >
>> > =A0 =A0 =A0 =A0/* For oom notifier event fd */
>> > =A0 =A0 =A0 =A0struct list_head oom_notify;
>> > -
>> > + =A0 =A0 =A0 /* For recording LRU-scan statistics */
>> > + =A0 =A0 =A0 struct scanstat scanstat;

Can we add this to mem_cgroup_stat_cpu ?

>> > =A0 =A0 =A0 =A0/*
>> > =A0 =A0 =A0 =A0 * Should we move charges of a task when a task is move=
d into this
>> > =A0 =A0 =A0 =A0 * mem_cgroup ? And what type of charges should we move=
 ?
>> > @@ -1634,6 +1686,28 @@ int mem_cgroup_select_victim_node(struct
>> > =A0}
>> > =A0#endif
>> >
>> > +
>> > +
>> > +static void mem_cgroup_record_scanstat(struct memcg_scanrecord *rec)
>> > +{
>> > + =A0 =A0 =A0 struct mem_cgroup *mem;
>> > + =A0 =A0 =A0 int context =3D rec->context;
>> > +
>> > + =A0 =A0 =A0 mem =3D rec->mem;
>> > + =A0 =A0 =A0 spin_lock(&mem->scanstat.lock);
>> > + =A0 =A0 =A0 mem->scanstat.stats[context] +=3D rec->nr_scanned;
>> > + =A0 =A0 =A0 mem->scanstat.stats[context + __FREED] +=3D rec->nr_free=
d;
>> > + =A0 =A0 =A0 mem->scanstat.stats[context + __ELAPSED] +=3D rec->elapp=
sed;
>> >
>> elapsed?
>>
>>
>> + =A0 =A0 =A0 spin_unlock(&mem->scanstat.lock);
>> > +
>> > + =A0 =A0 =A0 mem =3D rec->root;
>> > + =A0 =A0 =A0 spin_lock(&mem->scanstat.lock);
>> > + =A0 =A0 =A0 mem->scanstat.totalstats[context] +=3D rec->nr_scanned;
>> > + =A0 =A0 =A0 mem->scanstat.totalstats[context + __FREED] +=3D rec->nr=
_freed;
>> > + =A0 =A0 =A0 mem->scanstat.totalstats[context + __ELAPSED] +=3D rec->=
elappsed;
>> >
>>
>> elapsed?
>>
>> > + =A0 =A0 =A0 spin_unlock(&mem->scanstat.lock);
>> > +}
>> > +
>> > =A0/*
>> > =A0* Scan the hierarchy if needed to reclaim memory. We remember the l=
ast
>> > child
>> > =A0* we reclaimed from, so that we don't end up penalizing one child
>> > extensively
>> > @@ -1659,8 +1733,8 @@ static int mem_cgroup_hierarchical_recla
>> > =A0 =A0 =A0 =A0bool shrink =3D reclaim_options & MEM_CGROUP_RECLAIM_SH=
RINK;
>> > =A0 =A0 =A0 =A0bool check_soft =3D reclaim_options & MEM_CGROUP_RECLAI=
M_SOFT;
>> > =A0 =A0 =A0 =A0unsigned long excess;
>> > - =A0 =A0 =A0 unsigned long nr_scanned;
>> > =A0 =A0 =A0 =A0int visit;
>> > + =A0 =A0 =A0 struct memcg_scanrecord rec;
>> >
>> > =A0 =A0 =A0 =A0excess =3D res_counter_soft_limit_excess(&root_mem->res=
) >>
>> > PAGE_SHIFT;
>> >
>> > @@ -1668,6 +1742,15 @@ static int mem_cgroup_hierarchical_recla
>> > =A0 =A0 =A0 =A0if (!check_soft && root_mem->memsw_is_minimum)
>> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0noswap =3D true;
>> >
>> > + =A0 =A0 =A0 if (shrink)
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 rec.context =3D SCAN_BY_SHRINK;
>> > + =A0 =A0 =A0 else if (check_soft)
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 rec.context =3D SCAN_BY_SYSTEM;
>> > + =A0 =A0 =A0 else
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 rec.context =3D SCAN_BY_LIMIT;
>> > +
>> > + =A0 =A0 =A0 rec.root =3D root_mem;
>> >
>>
>>
>>
>> > +
>> > =A0again:
>> > =A0 =A0 =A0 =A0if (!shrink) {
>> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0visit =3D 0;
>> > @@ -1695,14 +1778,19 @@ again:
>> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0css_put(&victim->css);
>> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0continue;
>> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0}
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 rec.mem =3D victim;
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 rec.nr_scanned =3D 0;
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 rec.nr_freed =3D 0;
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 rec.elappsed =3D 0;
>> >
>> elapsed?
>>
>> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0/* we use swappiness of local cgroup */
>> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0if (check_soft) {
>> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0ret =3D mem_cgroup_shri=
nk_node_zone(victim, gfp_mask,
>> > - =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 noswap, =
zone, &nr_scanned);
>> > - =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 *total_scanned +=3D nr_s=
canned;
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 noswap, =
zone, &rec);
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 *total_scanned +=3D rec.=
nr_scanned;
>> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0} else
>> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0ret =3D try_to_free_mem=
_cgroup_pages(victim, gfp_mask,
>> > - =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 =A0 =A0 =A0 =A0 noswap);
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 =A0 =A0 =A0 =A0 noswap, &rec);
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 mem_cgroup_record_scanstat(&rec);
>> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0css_put(&victim->css);
>> >
>> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0total +=3D ret;
>> > @@ -3757,7 +3845,8 @@ try_to_free:
>> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0ret =3D -EINTR;
>> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0goto out;
>> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0}
>> > - =A0 =A0 =A0 =A0 =A0 =A0 =A0 progress =3D try_to_free_mem_cgroup_page=
s(mem, GFP_KERNEL,
>> > false);
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 progress =3D try_to_free_mem_cgroup_page=
s(mem,
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 GFP_KERN=
EL, false, NULL);
>> >
>>
>> So we don't record the stat for force_empty case?
>>
>
> yes, now. force_empty is used only for rmdir(). I don't think log is
> necessary for cgroup disappearing.

we might need to add that case later, since force_empty can also being
used as adding external pressure to the memcg.
>
>
>>
>> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0if (!progress) {
>> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0nr_retries--;
>> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0/* maybe some writeback=
 is necessary */
>> > @@ -4599,6 +4688,34 @@ static int mem_control_numa_stat_open(st
>> > =A0}
>> > =A0#endif /* CONFIG_NUMA */
>> >
>> > +static int mem_cgroup_scan_stat_read(struct cgroup *cgrp,
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 struct c=
ftype *cft,
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 struct c=
group_map_cb *cb)
>> > +{
>> > + =A0 =A0 =A0 struct mem_cgroup *mem =3D mem_cgroup_from_cont(cgrp);
>> > + =A0 =A0 =A0 int i;
>> > +
>> > + =A0 =A0 =A0 for (i =3D 0; i < NR_SCANSTATS; i++)
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 cb->fill(cb, scanstat_string[i], mem->sc=
anstat.stats[i]);
>> > + =A0 =A0 =A0 for (i =3D 0; i < NR_SCANSTATS; i++)
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 cb->fill(cb, total_scanstat_string[i],
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 mem->scanstat.totalstats=
[i]);
>> > + =A0 =A0 =A0 return 0;
>> > +}
>> > +
>> > +static int mem_cgroup_reset_scan_stat(struct cgroup *cgrp,
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 unsigned=
 int event)
>> > +{
>> > + =A0 =A0 =A0 struct mem_cgroup *mem =3D mem_cgroup_from_cont(cgrp);
>> > +
>> > + =A0 =A0 =A0 spin_lock(&mem->scanstat.lock);
>> > + =A0 =A0 =A0 memset(&mem->scanstat.stats, 0, sizeof(mem->scanstat.sta=
ts));
>> > + =A0 =A0 =A0 memset(&mem->scanstat.totalstats, 0,
>> > sizeof(mem->scanstat.totalstats));
>> > + =A0 =A0 =A0 spin_unlock(&mem->scanstat.lock);
>> > + =A0 =A0 =A0 return 0;
>> > +}
>> > +
>> > +
>> > =A0static struct cftype mem_cgroup_files[] =3D {
>> > =A0 =A0 =A0 =A0{
>> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0.name =3D "usage_in_bytes",
>> > @@ -4669,6 +4786,11 @@ static struct cftype mem_cgroup_files[]
>> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0.mode =3D S_IRUGO,
>> > =A0 =A0 =A0 =A0},
>> > =A0#endif
>> > + =A0 =A0 =A0 {
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 .name =3D "scan_stat",
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 .read_map =3D mem_cgroup_scan_stat_read,
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 .trigger =3D mem_cgroup_reset_scan_stat,
>> > + =A0 =A0 =A0 },
>> > =A0};
>> >
>> > =A0#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
>> > @@ -4932,6 +5054,7 @@ mem_cgroup_create(struct cgroup_subsys *
>> > =A0 =A0 =A0 =A0atomic_set(&mem->refcnt, 1);
>> > =A0 =A0 =A0 =A0mem->move_charge_at_immigrate =3D 0;
>> > =A0 =A0 =A0 =A0mutex_init(&mem->thresholds_lock);
>> > + =A0 =A0 =A0 spin_lock_init(&mem->scanstat.lock);
>> > =A0 =A0 =A0 =A0return &mem->css;
>> > =A0free_out:
>> > =A0 =A0 =A0 =A0__mem_cgroup_free(mem);
>> > Index: mmotm-0615/mm/vmscan.c
>> > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>> > --- mmotm-0615.orig/mm/vmscan.c
>> > +++ mmotm-0615/mm/vmscan.c
>> > @@ -2199,9 +2199,9 @@ unsigned long try_to_free_pages(struct z
>> > =A0#ifdef CONFIG_CGROUP_MEM_RES_CTLR
>> >
>> > =A0unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem,
>> > - =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 =A0 =A0 =A0 =A0 gfp_t gfp_mask, bool
>> > noswap,
>> > - =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 =A0 =A0 =A0 =A0 struct zone *zone,
>> > - =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 =A0 =A0 =A0 =A0 unsigned long *nr_scanned)
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 gfp_t gfp_mask, bool noswap,
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 struct zone *zone,
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 struct memcg_scanrecord *rec)
>> > =A0{
>> > =A0 =A0 =A0 =A0struct scan_control sc =3D {
>> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0.nr_scanned =3D 0,
>> > @@ -2213,6 +2213,7 @@ unsigned long mem_cgroup_shrink_node_zon
>> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0.order =3D 0,
>> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0.mem_cgroup =3D mem,
>> > =A0 =A0 =A0 =A0};
>> > + =A0 =A0 =A0 unsigned long start, end;
>> >
>> > =A0 =A0 =A0 =A0sc.gfp_mask =3D (gfp_mask & GFP_RECLAIM_MASK) |
>> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0(GFP_HIGHUSER_MOVABLE &=
 ~GFP_RECLAIM_MASK);
>> > @@ -2221,6 +2222,7 @@ unsigned long mem_cgroup_shrink_node_zon
>> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0sc.may_writepage,
>> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0sc.gfp_mask);
>> >
>> > + =A0 =A0 =A0 start =3D sched_clock();
>> > =A0 =A0 =A0 =A0/*
>> > =A0 =A0 =A0 =A0 * NOTE: Although we can get the priority field, using =
it
>> > =A0 =A0 =A0 =A0 * here is not a good idea, since it limits the pages w=
e can scan.
>> > @@ -2229,19 +2231,27 @@ unsigned long mem_cgroup_shrink_node_zon
>> > =A0 =A0 =A0 =A0 * the priority and make it zero.
>> > =A0 =A0 =A0 =A0 */
>> > =A0 =A0 =A0 =A0shrink_zone(0, zone, &sc);
>> > + =A0 =A0 =A0 end =3D sched_clock();
>> > +
>> > + =A0 =A0 =A0 if (rec) {
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 rec->nr_scanned +=3D sc.nr_scanned;
>> >
>>
>>
>>
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 rec->nr_freed +=3D sc.nr_reclaimed;
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 rec->elappsed +=3D end - start;
>> >
>> elapsed?
>>
>> > + =A0 =A0 =A0 }
>> >
>> > =A0 =A0 =A0 =A0trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_recla=
imed);
>> >
>> > - =A0 =A0 =A0 *nr_scanned =3D sc.nr_scanned;
>> > =A0 =A0 =A0 =A0return sc.nr_reclaimed;
>> > =A0}
>> >
>> > =A0unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_c=
ont,
>> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 =A0 =A0 gfp_t gfp_mask,
>> > - =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 =A0 =A0bool noswap)
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 =A0 =A0bool noswap,
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 =A0 =A0struct memcg_scanrecord *rec)
>> > =A0{
>> > =A0 =A0 =A0 =A0struct zonelist *zonelist;
>> > =A0 =A0 =A0 =A0unsigned long nr_reclaimed;
>> > + =A0 =A0 =A0 unsigned long start, end;
>> > =A0 =A0 =A0 =A0int nid;
>> > =A0 =A0 =A0 =A0struct scan_control sc =3D {
>> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0.may_writepage =3D !laptop_mode,
>> > @@ -2259,6 +2269,7 @@ unsigned long try_to_free_mem_cgroup_pag
>> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0.gfp_mask =3D sc.gfp_mask,
>> > =A0 =A0 =A0 =A0};
>> >
>> > + =A0 =A0 =A0 start =3D sched_clock();
>> > =A0 =A0 =A0 =A0/*
>> > =A0 =A0 =A0 =A0 * Unlike direct reclaim via alloc_pages(), memcg's rec=
laim doesn't
>> > =A0 =A0 =A0 =A0 * take care of from where we get pages. So the node wh=
ere we start
>> > the
>> > @@ -2273,6 +2284,12 @@ unsigned long try_to_free_mem_cgroup_pag
>> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 =A0 =A0 =A0sc.gfp_mask);
>> >
>> > =A0 =A0 =A0 =A0nr_reclaimed =3D do_try_to_free_pages(zonelist, &sc, &s=
hrink);
>> > + =A0 =A0 =A0 end =3D sched_clock();
>> > + =A0 =A0 =A0 if (rec) {
>> > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 rec->nr_scanned +=3D sc.nr_scanned;
>> >
>>
>> sc.nr_scanned only contains the nr_scanned of last
>> priority do_try_to_free_pages(). we need to reset it to total_scanned be=
fore
>> return. I am looking at v3.0-rc3 .
>>
>
> Hm. ok, then, total_reclaimed in softlimit is buggy, too.
> I'll check.

Thanks

--Ying
>
> Thanks,
> -Kame
>
>

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