On Mon, Mar 19, 2012 at 1:27 AM, Zhu Yanhai <zhu.yanhai@xxxxxxxxx> wrote:
> 2011/4/15 KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>:
>> On Thu, 14 Apr 2011 15:54:26 -0700
>> Ying Han <yinghan@xxxxxxxxxx> wrote:
>>
>>> After reclaiming each node per memcg, it checks mem_cgroup_watermark_ok()
>>> and breaks the priority loop if it returns true. The per-memcg zone will
>>> be marked as "unreclaimable" if the scanning rate is much greater than the
>>> reclaiming rate on the per-memcg LRU. The bit is cleared when there is a
>>> page charged to the memcg being freed. Kswapd breaks the priority loop if
>>> all the zones are marked as "unreclaimable".
>>>
>>> changelog v4..v3:
>>> 1. split off from the per-memcg background reclaim patch in V3.
>>>
>>> Signed-off-by: Ying Han <yinghan@xxxxxxxxxx>
>>> ---
>>> include/linux/memcontrol.h | 30 ++++++++++++++
>>> include/linux/swap.h | 2 +
>>> mm/memcontrol.c | 96 ++++++++++++++++++++++++++++++++++++++++++++
>>> mm/vmscan.c | 19 +++++++++
>>> 4 files changed, 147 insertions(+), 0 deletions(-)
>>>
>>> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
>>> index d4ff7f2..a8159f5 100644
>>> --- a/include/linux/memcontrol.h
>>> +++ b/include/linux/memcontrol.h
>>> @@ -155,6 +155,12 @@ static inline void mem_cgroup_dec_page_stat(struct page *page,
>>> unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
>>> gfp_t gfp_mask);
>>> u64 mem_cgroup_get_limit(struct mem_cgroup *mem);
>>> +void mem_cgroup_clear_unreclaimable(struct mem_cgroup *mem, struct page *page);
>>> +bool mem_cgroup_zone_reclaimable(struct mem_cgroup *mem, int nid, int zid);
>>> +bool mem_cgroup_mz_unreclaimable(struct mem_cgroup *mem, struct zone *zone);
>>> +void mem_cgroup_mz_set_unreclaimable(struct mem_cgroup *mem, struct zone *zone);
>>> +void mem_cgroup_mz_pages_scanned(struct mem_cgroup *mem, struct zone* zone,
>>> + unsigned long nr_scanned);
>>>
>>> #ifdef CONFIG_TRANSPARENT_HUGEPAGE
>>> void mem_cgroup_split_huge_fixup(struct page *head, struct page *tail);
>>> @@ -345,6 +351,25 @@ static inline void mem_cgroup_dec_page_stat(struct page *page,
>>> {
>>> }
>>>
>>> +static inline void mem_cgroup_mz_pages_scanned(struct mem_cgroup *mem,
>>> + struct zone *zone,
>>> + unsigned long nr_scanned)
>>> +{
>>> +}
>>> +
>>> +static inline void mem_cgroup_clear_unreclaimable(struct page *page,
>>> + struct zone *zone)
>>> +{
>>> +}
>>> +static inline void mem_cgroup_mz_set_unreclaimable(struct mem_cgroup *mem,
>>> + struct zone *zone)
>>> +{
>>> +}
>>> +static inline bool mem_cgroup_mz_unreclaimable(struct mem_cgroup *mem,
>>> + struct zone *zone)
>>> +{
>>> +}
>>> +
>>> static inline
>>> unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
>>> gfp_t gfp_mask)
>>> @@ -363,6 +388,11 @@ static inline void mem_cgroup_split_huge_fixup(struct page *head,
>>> {
>>> }
>>>
>>> +static inline bool mem_cgroup_zone_reclaimable(struct mem_cgroup *mem, int nid,
>>> + int zid)
>>> +{
>>> + return false;
>>> +}
>>> #endif /* CONFIG_CGROUP_MEM_CONT */
>>>
>>> #if !defined(CONFIG_CGROUP_MEM_RES_CTLR) || !defined(CONFIG_DEBUG_VM)
>>> diff --git a/include/linux/swap.h b/include/linux/swap.h
>>> index 17e0511..319b800 100644
>>> --- a/include/linux/swap.h
>>> +++ b/include/linux/swap.h
>>> @@ -160,6 +160,8 @@ enum {
>>> SWP_SCANNING = (1 << 8), /* refcount in scan_swap_map */
>>> };
>>>
>>> +#define ZONE_RECLAIMABLE_RATE 6
>>> +
>>> #define SWAP_CLUSTER_MAX 32
>>> #define COMPACT_CLUSTER_MAX SWAP_CLUSTER_MAX
>>>
>>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
>>> index e22351a..da6a130 100644
>>> --- a/mm/memcontrol.c
>>> +++ b/mm/memcontrol.c
>>> @@ -133,7 +133,10 @@ struct mem_cgroup_per_zone {
>>> bool on_tree;
>>> struct mem_cgroup *mem; /* Back pointer, we cannot */
>>> /* use container_of */
>>> + unsigned long pages_scanned; /* since last reclaim */
>>> + bool all_unreclaimable; /* All pages pinned */
>>> };
>>> +
>>> /* Macro for accessing counter */
>>> #define MEM_CGROUP_ZSTAT(mz, idx) ((mz)->count[(idx)])
>>>
>>> @@ -1135,6 +1138,96 @@ mem_cgroup_get_reclaim_stat_from_page(struct page *page)
>>> return &mz->reclaim_stat;
>>> }
>>>
>>> +static unsigned long mem_cgroup_zone_reclaimable_pages(
>>> + struct mem_cgroup_per_zone *mz)
>>> +{
>>> + int nr;
>>> + nr = MEM_CGROUP_ZSTAT(mz, LRU_ACTIVE_FILE) +
>>> + MEM_CGROUP_ZSTAT(mz, LRU_INACTIVE_FILE);
>>> +
>>> + if (nr_swap_pages > 0)
>>> + nr += MEM_CGROUP_ZSTAT(mz, LRU_ACTIVE_ANON) +
>>> + MEM_CGROUP_ZSTAT(mz, LRU_INACTIVE_ANON);
>>> +
>>> + return nr;
>>> +}
>>> +
>>> +void mem_cgroup_mz_pages_scanned(struct mem_cgroup *mem, struct zone* zone,
>>> + unsigned long nr_scanned)
>>> +{
>>> + struct mem_cgroup_per_zone *mz = NULL;
>>> + int nid = zone_to_nid(zone);
>>> + int zid = zone_idx(zone);
>>> +
>>> + if (!mem)
>>> + return;
>>> +
>>> + mz = mem_cgroup_zoneinfo(mem, nid, zid);
>>> + if (mz)
>>> + mz->pages_scanned += nr_scanned;
>>> +}
>>> +
>>> +bool mem_cgroup_zone_reclaimable(struct mem_cgroup *mem, int nid, int zid)
>>> +{
>>> + struct mem_cgroup_per_zone *mz = NULL;
>>> +
>>> + if (!mem)
>>> + return 0;
>>> +
>>> + mz = mem_cgroup_zoneinfo(mem, nid, zid);
>>> + if (mz)
>>> + return mz->pages_scanned <
>>> + mem_cgroup_zone_reclaimable_pages(mz) *
>>> + ZONE_RECLAIMABLE_RATE;
>>> + return 0;
>>> +}
>>> +
>>> +bool mem_cgroup_mz_unreclaimable(struct mem_cgroup *mem, struct zone *zone)
>>> +{
>>> + struct mem_cgroup_per_zone *mz = NULL;
>>> + int nid = zone_to_nid(zone);
>>> + int zid = zone_idx(zone);
>>> +
>>> + if (!mem)
>>> + return false;
>>> +
>>> + mz = mem_cgroup_zoneinfo(mem, nid, zid);
>>> + if (mz)
>>> + return mz->all_unreclaimable;
>>> +
>>> + return false;
>>> +}
>>> +
>>> +void mem_cgroup_mz_set_unreclaimable(struct mem_cgroup *mem, struct zone *zone)
>>> +{
>>> + struct mem_cgroup_per_zone *mz = NULL;
>>> + int nid = zone_to_nid(zone);
>>> + int zid = zone_idx(zone);
>>> +
>>> + if (!mem)
>>> + return;
>>> +
>>> + mz = mem_cgroup_zoneinfo(mem, nid, zid);
>>> + if (mz)
>>> + mz->all_unreclaimable = true;
>>> +}
>>> +
>>> +void mem_cgroup_clear_unreclaimable(struct mem_cgroup *mem, struct page *page)
>>> +{
>>> + struct mem_cgroup_per_zone *mz = NULL;
>>> +
>>> + if (!mem)
>>> + return;
>>> +
>>> + mz = page_cgroup_zoneinfo(mem, page);
>>> + if (mz) {
>>> + mz->pages_scanned = 0;
>>> + mz->all_unreclaimable = false;
>>> + }
>>> +
>>> + return;
>>> +}
>>> +
>>> unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
>>> struct list_head *dst,
>>> unsigned long *scanned, int order,
>>> @@ -2801,6 +2894,7 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype)
>>> * special functions.
>>> */
>>>
>>> + mem_cgroup_clear_unreclaimable(mem, page);
>>
>> Hmm, this will easily cause cache ping-pong. (free_page() clears it after taking
>> zone->lock....in batched manner.)
>>
>> Could you consider a way to make this low cost ?
>>
>> One way is using memcg_check_event() with some low event trigger.
>> Second way is usign memcg_batch.
>> In many case, we can expect a chunk of free pages are from the same zone.
>> Then, add a new member to batch_memcg as
>>
>> struct memcg_batch_info {
>> .....
>> struct zone *zone; # a zone page is last uncharged.
>> ...
>> }
>>
>> Then,
>> ==
>> static void mem_cgroup_do_uncharge(struct mem_cgroup *mem,
>> unsigned int nr_pages,
>> + struct page *page,
>> const enum charge_type ctype)
>> {
>> struct memcg_batch_info *batch = NULL;
>> .....
>>
>> if (batch->zone != page_zone(page)) {
>> mem_cgroup_clear_unreclaimable(mem, page);
>> }
>> direct_uncharge:
>> mem_cgroup_clear_unreclaimable(mem, page);
>> ....
>> }
>> ==
>>
>> This will reduce overhead dramatically.
>>
>
> Excuse me but I don't quite understand this part, IMHO this is to
> avoid call mem_cgroup_clear_unreclaimable() against each single page
> during a munmap()/free_pages() including many pages to free, which is
> unnecessary because the zone will turn into 'reclaimable' at the first
> page uncharged.
> Then why can't we just say,
> if (mem_cgroup_zoneinfo(mem, page_to_nid(page), page_zonenum(page))->all_unreclaimable) {
> mem_cgroup_clear_unreclaimable(mem, page);
> }
Are you suggesting to replace the batching w/ the code above?
--Ying
> --
> Thanks,
> Zhu Yanhai
>
>
>>
>>
>>> unlock_page_cgroup(pc);
>>> /*
>>> * even after unlock, we have mem->res.usage here and this memcg
>>> @@ -4569,6 +4663,8 @@ static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *mem, int node)
>>> mz->usage_in_excess = 0;
>>> mz->on_tree = false;
>>> mz->mem = mem;
>>> + mz->pages_scanned = 0;
>>> + mz->all_unreclaimable = false;
>>> }
>>> return 0;
>>> }
>>> diff --git a/mm/vmscan.c b/mm/vmscan.c
>>> index b8345d2..c081112 100644
>>> --- a/mm/vmscan.c
>>> +++ b/mm/vmscan.c
>>> @@ -1414,6 +1414,9 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone,
>>> ISOLATE_BOTH : ISOLATE_INACTIVE,
>>> zone, sc->mem_cgroup,
>>> 0, file);
>>> +
>>> + mem_cgroup_mz_pages_scanned(sc->mem_cgroup, zone, nr_scanned);
>>> +
>>> /*
>>> * mem_cgroup_isolate_pages() keeps track of
>>> * scanned pages on its own.
>>> @@ -1533,6 +1536,7 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
>>> * mem_cgroup_isolate_pages() keeps track of
>>> * scanned pages on its own.
>>> */
>>> + mem_cgroup_mz_pages_scanned(sc->mem_cgroup, zone, pgscanned);
>>> }
>>>
>>> reclaim_stat->recent_scanned[file] += nr_taken;
>>> @@ -2648,6 +2652,7 @@ static void balance_pgdat_node(pg_data_t *pgdat, int order,
>>> unsigned long total_scanned = 0;
>>> struct mem_cgroup *mem_cont = sc->mem_cgroup;
>>> int priority = sc->priority;
>>> + int nid = pgdat->node_id;
>>>
>>> /*
>>> * Now scan the zone in the dma->highmem direction, and we scan
>>> @@ -2664,10 +2669,20 @@ static void balance_pgdat_node(pg_data_t *pgdat, int order,
>>> if (!populated_zone(zone))
>>> continue;
>>>
>>> + if (mem_cgroup_mz_unreclaimable(mem_cont, zone) &&
>>> + priority != DEF_PRIORITY)
>>> + continue;
>>> +
>>> sc->nr_scanned = 0;
>>> shrink_zone(priority, zone, sc);
>>> total_scanned += sc->nr_scanned;
>>>
>>> + if (mem_cgroup_mz_unreclaimable(mem_cont, zone))
>>> + continue;
>>> +
>>> + if (!mem_cgroup_zone_reclaimable(mem_cont, nid, i))
>>> + mem_cgroup_mz_set_unreclaimable(mem_cont, zone);
>>> +
>>> /*
>>> * If we've done a decent amount of scanning and
>>> * the reclaim ratio is low, start doing writepage
>>> @@ -2752,6 +2767,10 @@ loop_again:
>>>
>>> if (!populated_zone(zone))
>>> continue;
>>> +
>>> + if (!mem_cgroup_mz_unreclaimable(mem_cont,
>>> + zone))
>>> +
>>
>> Ah, okay. this will work.
>>
>> Thanks,
>> -Kame
>>
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