On Tue, Jun 21, 2011 at 5:20 PM, KAMEZAWA Hiroyuki
<kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote:
> On Mon, 20 Jun 2011 23:49:54 -0700
> Ying Han <yinghan@xxxxxxxxxx> wrote:
>
>> On Wed, Jun 15, 2011 at 8:53 PM, KAMEZAWA Hiroyuki <
>> kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote:
>>
>> > From e08990dd9ada13cf236bec1ef44b207436434b8e Mon Sep 17 00:00:00 2001
>> > From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
>> > 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 because
>> > we considered we needed to make a concensus for such new APIs.
>> >
>> > This patch is a trial to add memory.scan_stat. This shows
>> > - the number of scanned pages
>> > - the number of recleimed pages
>> > - the number of elaplsed time (including sleep/pause time)
>> > for both of direct/soft reclaim and shrinking caused by changing limit
>> > or force_empty.
>> >
>> > The biggest difference with oringinal Ying's one is that this file
>> > can be reset by some write, as
>> >
>> > # 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 memcg
>> 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@xxxxxxxxxxxxxx>
>> > ---
>> > Documentation/cgroups/memory.txt | 33 +++++++++
>> > include/linux/memcontrol.h | 16 ++++
>> > include/linux/swap.h | 6 -
>> > mm/memcontrol.c | 135
>> > +++++++++++++++++++++++++++++++++++++--
>> > mm/vmscan.c | 27 ++++++-
>> > 5 files changed, 199 insertions(+), 18 deletions(-)
>> >
>> > Index: mmotm-0615/Documentation/cgroups/memory.txt
>> > ===================================================================
>> > --- 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.
>> >
>> > 5.2 stat file
>> >
>> > -memory.stat file includes following statistics
>> > +5.2.1 memory.stat file includes following statistics
>> >
>> > # per-memory cgroup local status
>> > cache - # of bytes of page cache memory.
>> > @@ -438,6 +438,37 @@ Note:
>> > file_mapped is accounted only when the memory cgroup is owner of
>> > page
>> > 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 - # of freed pages at hitting limit.
>> > +elapsed_ns_by_limit - nano sec of elappsed time at LRU scan at
>> > + hitting limit.(this includes sleep
>> > time.)
>> >
>> elapsed?
>>
>> > +
>> > +scanned_pages_by_system - # of scanned pages by the kernel.
>> > + (Now, this value means global memory reclaim
>> > + caused by system memory shortage with a hint
>> > + of softlimit. "No soft limit" case will be
>> > + supported in future.)
>> > +freed_pages_by_system - # of freed pages by the kernel.
>> > +elapsed_ns_by_system - nano sec of elappsed time by kernel.
>> > +
>> > +scanned_pages_by_shrink - # of scanned pages by shrinking.
>> > + (i.e. changes of limit, force_empty,
>> > etc.)
>> > +freed_pages_by_shrink - # of freed pages by shirkining.
>> > +elappsed_ns_by_shrink - 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 scan
>> stat as well.
>>
>
> yes.
>
>
>> +
>> > +
>> > 5.3 swappiness
>> >
>> > Similar to /proc/sys/vm/swappiness, but affecting a hierarchy of groups
>> > only.
>> > Index: mmotm-0615/include/linux/memcontrol.h
>> > ===================================================================
>> > --- mmotm-0615.orig/include/linux/memcontrol.h
>> > +++ mmotm-0615/include/linux/memcontrol.h
>> > @@ -120,6 +120,22 @@ struct zone_reclaim_stat*
>> > mem_cgroup_get_reclaim_stat_from_page(struct page *page);
>> > extern void mem_cgroup_print_oom_info(struct mem_cgroup *memcg,
>> > struct task_struct *p);
>> > +struct memcg_scanrecord {
>> > + struct mem_cgroup *mem; /* scanend memory cgroup */
>> > + struct mem_cgroup *root; /* scan target hierarchy root */
>> > + int context; /* scanning context (see memcontrol.c) */
>> > + unsigned long nr_scanned; /* the number of scanned pages */
>> > + unsigned long nr_freed; /* the number of freed pages */
>> > + unsigned long elappsed; /* nsec of time elapsed while scanning */
>> >
>> elapsed?
>>
>> > +};
>> > +
>> > +extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem,
>> > + gfp_t gfp_mask, bool
>> > noswap,
>> > + struct memcg_scanrecord
>> > *rec);
>> > +extern unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem,
>> > + gfp_t gfp_mask, bool
>> > noswap,
>> > + struct zone *zone,
>> > + struct memcg_scanrecord
>> > *rec);
>> >
>> > #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
>> > extern int do_swap_account;
>> > Index: mmotm-0615/include/linux/swap.h
>> > ===================================================================
>> > --- 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
>> > /* linux/mm/vmscan.c */
>> > extern unsigned long try_to_free_pages(struct zonelist *zonelist, int
>> > order,
>> > gfp_t gfp_mask, nodemask_t *mask);
>> > -extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem,
>> > - gfp_t gfp_mask, bool
>> > noswap);
>> > -extern unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem,
>> > - gfp_t gfp_mask, bool
>> > noswap,
>> > - struct zone *zone,
>> > - unsigned long *nr_scanned);
>> > extern int __isolate_lru_page(struct page *page, int mode, int file);
>> > extern unsigned long shrink_all_memory(unsigned long nr_pages);
>> > extern int vm_swappiness;
>> > Index: mmotm-0615/mm/memcontrol.c
>> > ===================================================================
>> > --- mmotm-0615.orig/mm/memcontrol.c
>> > +++ mmotm-0615/mm/memcontrol.c
>> > @@ -203,6 +203,57 @@ struct mem_cgroup_eventfd_list {
>> > static void mem_cgroup_threshold(struct mem_cgroup *mem);
>> > static void mem_cgroup_oom_notify(struct mem_cgroup *mem);
>> >
>> > +enum {
>> > + SCAN_BY_LIMIT,
>> > + FREED_BY_LIMIT,
>> > + ELAPSED_BY_LIMIT,
>> > +
>> > + SCAN_BY_SYSTEM,
>> > + FREED_BY_SYSTEM,
>> > + ELAPSED_BY_SYSTEM,
>> > +
>> > + SCAN_BY_SHRINK,
>> > + FREED_BY_SHRINK,
>> > + ELAPSED_BY_SHRINK,
>> > + NR_SCANSTATS,
>> > +};
>> > +#define __FREED (1)
>> > +#define __ELAPSED (2)
>> >
>>
>> /tab/space/
>>
>>
>> > +
>> > +struct scanstat {
>> > + spinlock_t lock;
>> > + unsigned long stats[NR_SCANSTATS]; /* local statistics */
>> > + unsigned long totalstats[NR_SCANSTATS]; /* hierarchical */
>> > +};
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] = {
>> > + "scanned_pages_by_limit",
>> > + "freed_pages_by_limit",
>> > + "elapsed_ns_by_limit",
>> > +
>> > + "scanned_pages_by_system",
>> > + "freed_pages_by_system",
>> > + "elapsed_ns_by_system",
>> > +
>> > + "scanned_pages_by_shrink",
>> > + "freed_pages_by_shrink",
>> > + "elappsed_ns_by_shrink",
>> >
>> elapsed?
>>
>> > +};
>> > +
>> > +const char *total_scanstat_string[NR_SCANSTATS] = {
>> > + "total_scanned_pages_by_limit",
>> > + "total_freed_pages_by_limit",
>> > + "total_elapsed_ns_by_hierarchical",
>> >
>>
>> typo?
>>
>>
>> > +
>> > + "total_scanned_pages_by_system",
>> > + "total_freed_pages_by_system",
>> > + "total_elapsed_ns_by_system",
>> > +
>> > + "total_scanned_pages_by_shrink",
>> > + "total_freed_pages_by_shrink",
>> > + "total_elapsed_ns_by_shrink",
>> > +};
>> > +
>> > /*
>> > * The memory controller data structure. The memory controller controls
>> > both
>> > * page cache and RSS per cgroup. We would eventually like to provide
>> > @@ -264,7 +315,8 @@ struct mem_cgroup {
>> >
>> > /* For oom notifier event fd */
>> > struct list_head oom_notify;
>> > -
>> > + /* For recording LRU-scan statistics */
>> > + struct scanstat scanstat;
Can we add this to mem_cgroup_stat_cpu ?
>> > /*
>> > * Should we move charges of a task when a task is moved into this
>> > * mem_cgroup ? And what type of charges should we move ?
>> > @@ -1634,6 +1686,28 @@ int mem_cgroup_select_victim_node(struct
>> > }
>> > #endif
>> >
>> > +
>> > +
>> > +static void mem_cgroup_record_scanstat(struct memcg_scanrecord *rec)
>> > +{
>> > + struct mem_cgroup *mem;
>> > + int context = rec->context;
>> > +
>> > + mem = rec->mem;
>> > + spin_lock(&mem->scanstat.lock);
>> > + mem->scanstat.stats[context] += rec->nr_scanned;
>> > + mem->scanstat.stats[context + __FREED] += rec->nr_freed;
>> > + mem->scanstat.stats[context + __ELAPSED] += rec->elappsed;
>> >
>> elapsed?
>>
>>
>> + spin_unlock(&mem->scanstat.lock);
>> > +
>> > + mem = rec->root;
>> > + spin_lock(&mem->scanstat.lock);
>> > + mem->scanstat.totalstats[context] += rec->nr_scanned;
>> > + mem->scanstat.totalstats[context + __FREED] += rec->nr_freed;
>> > + mem->scanstat.totalstats[context + __ELAPSED] += rec->elappsed;
>> >
>>
>> elapsed?
>>
>> > + spin_unlock(&mem->scanstat.lock);
>> > +}
>> > +
>> > /*
>> > * Scan the hierarchy if needed to reclaim memory. We remember the last
>> > child
>> > * we reclaimed from, so that we don't end up penalizing one child
>> > extensively
>> > @@ -1659,8 +1733,8 @@ static int mem_cgroup_hierarchical_recla
>> > bool shrink = reclaim_options & MEM_CGROUP_RECLAIM_SHRINK;
>> > bool check_soft = reclaim_options & MEM_CGROUP_RECLAIM_SOFT;
>> > unsigned long excess;
>> > - unsigned long nr_scanned;
>> > int visit;
>> > + struct memcg_scanrecord rec;
>> >
>> > excess = res_counter_soft_limit_excess(&root_mem->res) >>
>> > PAGE_SHIFT;
>> >
>> > @@ -1668,6 +1742,15 @@ static int mem_cgroup_hierarchical_recla
>> > if (!check_soft && root_mem->memsw_is_minimum)
>> > noswap = true;
>> >
>> > + if (shrink)
>> > + rec.context = SCAN_BY_SHRINK;
>> > + else if (check_soft)
>> > + rec.context = SCAN_BY_SYSTEM;
>> > + else
>> > + rec.context = SCAN_BY_LIMIT;
>> > +
>> > + rec.root = root_mem;
>> >
>>
>>
>>
>> > +
>> > again:
>> > if (!shrink) {
>> > visit = 0;
>> > @@ -1695,14 +1778,19 @@ again:
>> > css_put(&victim->css);
>> > continue;
>> > }
>> > + rec.mem = victim;
>> > + rec.nr_scanned = 0;
>> > + rec.nr_freed = 0;
>> > + rec.elappsed = 0;
>> >
>> elapsed?
>>
>> > /* we use swappiness of local cgroup */
>> > if (check_soft) {
>> > ret = mem_cgroup_shrink_node_zone(victim, gfp_mask,
>> > - noswap, zone, &nr_scanned);
>> > - *total_scanned += nr_scanned;
>> > + noswap, zone, &rec);
>> > + *total_scanned += rec.nr_scanned;
>> > } else
>> > ret = try_to_free_mem_cgroup_pages(victim, gfp_mask,
>> > - noswap);
>> > + noswap, &rec);
>> > + mem_cgroup_record_scanstat(&rec);
>> > css_put(&victim->css);
>> >
>> > total += ret;
>> > @@ -3757,7 +3845,8 @@ try_to_free:
>> > ret = -EINTR;
>> > goto out;
>> > }
>> > - progress = try_to_free_mem_cgroup_pages(mem, GFP_KERNEL,
>> > false);
>> > + progress = try_to_free_mem_cgroup_pages(mem,
>> > + GFP_KERNEL, 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.
>
>
>>
>> > if (!progress) {
>> > nr_retries--;
>> > /* maybe some writeback is necessary */
>> > @@ -4599,6 +4688,34 @@ static int mem_control_numa_stat_open(st
>> > }
>> > #endif /* CONFIG_NUMA */
>> >
>> > +static int mem_cgroup_scan_stat_read(struct cgroup *cgrp,
>> > + struct cftype *cft,
>> > + struct cgroup_map_cb *cb)
>> > +{
>> > + struct mem_cgroup *mem = mem_cgroup_from_cont(cgrp);
>> > + int i;
>> > +
>> > + for (i = 0; i < NR_SCANSTATS; i++)
>> > + cb->fill(cb, scanstat_string[i], mem->scanstat.stats[i]);
>> > + for (i = 0; i < NR_SCANSTATS; i++)
>> > + cb->fill(cb, total_scanstat_string[i],
>> > + mem->scanstat.totalstats[i]);
>> > + return 0;
>> > +}
>> > +
>> > +static int mem_cgroup_reset_scan_stat(struct cgroup *cgrp,
>> > + unsigned int event)
>> > +{
>> > + struct mem_cgroup *mem = mem_cgroup_from_cont(cgrp);
>> > +
>> > + spin_lock(&mem->scanstat.lock);
>> > + memset(&mem->scanstat.stats, 0, sizeof(mem->scanstat.stats));
>> > + memset(&mem->scanstat.totalstats, 0,
>> > sizeof(mem->scanstat.totalstats));
>> > + spin_unlock(&mem->scanstat.lock);
>> > + return 0;
>> > +}
>> > +
>> > +
>> > static struct cftype mem_cgroup_files[] = {
>> > {
>> > .name = "usage_in_bytes",
>> > @@ -4669,6 +4786,11 @@ static struct cftype mem_cgroup_files[]
>> > .mode = S_IRUGO,
>> > },
>> > #endif
>> > + {
>> > + .name = "scan_stat",
>> > + .read_map = mem_cgroup_scan_stat_read,
>> > + .trigger = mem_cgroup_reset_scan_stat,
>> > + },
>> > };
>> >
>> > #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
>> > @@ -4932,6 +5054,7 @@ mem_cgroup_create(struct cgroup_subsys *
>> > atomic_set(&mem->refcnt, 1);
>> > mem->move_charge_at_immigrate = 0;
>> > mutex_init(&mem->thresholds_lock);
>> > + spin_lock_init(&mem->scanstat.lock);
>> > return &mem->css;
>> > free_out:
>> > __mem_cgroup_free(mem);
>> > Index: mmotm-0615/mm/vmscan.c
>> > ===================================================================
>> > --- mmotm-0615.orig/mm/vmscan.c
>> > +++ mmotm-0615/mm/vmscan.c
>> > @@ -2199,9 +2199,9 @@ unsigned long try_to_free_pages(struct z
>> > #ifdef CONFIG_CGROUP_MEM_RES_CTLR
>> >
>> > unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem,
>> > - gfp_t gfp_mask, bool
>> > noswap,
>> > - struct zone *zone,
>> > - unsigned long *nr_scanned)
>> > + gfp_t gfp_mask, bool noswap,
>> > + struct zone *zone,
>> > + struct memcg_scanrecord *rec)
>> > {
>> > struct scan_control sc = {
>> > .nr_scanned = 0,
>> > @@ -2213,6 +2213,7 @@ unsigned long mem_cgroup_shrink_node_zon
>> > .order = 0,
>> > .mem_cgroup = mem,
>> > };
>> > + unsigned long start, end;
>> >
>> > sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
>> > (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK);
>> > @@ -2221,6 +2222,7 @@ unsigned long mem_cgroup_shrink_node_zon
>> > sc.may_writepage,
>> > sc.gfp_mask);
>> >
>> > + start = sched_clock();
>> > /*
>> > * NOTE: Although we can get the priority field, using it
>> > * here is not a good idea, since it limits the pages we can scan.
>> > @@ -2229,19 +2231,27 @@ unsigned long mem_cgroup_shrink_node_zon
>> > * the priority and make it zero.
>> > */
>> > shrink_zone(0, zone, &sc);
>> > + end = sched_clock();
>> > +
>> > + if (rec) {
>> > + rec->nr_scanned += sc.nr_scanned;
>> >
>>
>>
>>
>> > + rec->nr_freed += sc.nr_reclaimed;
>> > + rec->elappsed += end - start;
>> >
>> elapsed?
>>
>> > + }
>> >
>> > trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed);
>> >
>> > - *nr_scanned = sc.nr_scanned;
>> > return sc.nr_reclaimed;
>> > }
>> >
>> > unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont,
>> > gfp_t gfp_mask,
>> > - bool noswap)
>> > + bool noswap,
>> > + struct memcg_scanrecord *rec)
>> > {
>> > struct zonelist *zonelist;
>> > unsigned long nr_reclaimed;
>> > + unsigned long start, end;
>> > int nid;
>> > struct scan_control sc = {
>> > .may_writepage = !laptop_mode,
>> > @@ -2259,6 +2269,7 @@ unsigned long try_to_free_mem_cgroup_pag
>> > .gfp_mask = sc.gfp_mask,
>> > };
>> >
>> > + start = sched_clock();
>> > /*
>> > * Unlike direct reclaim via alloc_pages(), memcg's reclaim doesn't
>> > * take care of from where we get pages. So the node where we start
>> > the
>> > @@ -2273,6 +2284,12 @@ unsigned long try_to_free_mem_cgroup_pag
>> > sc.gfp_mask);
>> >
>> > nr_reclaimed = do_try_to_free_pages(zonelist, &sc, &shrink);
>> > + end = sched_clock();
>> > + if (rec) {
>> > + rec->nr_scanned += 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 before
>> 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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