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From: Alex Shi <alex.shi@linux.alibaba.com>
To: alexander.h.duyck@intel.com
Cc: akpm@linux-foundation.org, alexander.duyck@gmail.com,
	aryabinin@virtuozzo.com, cgroups@vger.kernel.org,
	daniel.m.jordan@oracle.com, hannes@cmpxchg.org, hughd@google.com,
	iamjoonsoo.kim@lge.com, khlebnikov@yandex-team.ru,
	kirill@shutemov.name, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, lkp@intel.com, mgorman@techsingularity.net,
	richard.weiyang@gmail.com, rong.a.chen@intel.com,
	shakeelb@google.com, tglx@linutronix.de, tj@kernel.org,
	willy@infradead.org, yang.shi@linux.alibaba.com
Subject: Re: [PATCH RFC] mm: Add function for testing if the current lruvec lock is valid
Date: Sat, 1 Aug 2020 07:54:48 +0800
Message-ID: <0c0a415a-52a0-5c06-b4be-80cbd3cb49c2@linux.alibaba.com> (raw)
In-Reply-To: <159622999150.2576729.14455020813024958573.stgit@ahduyck-desk1.jf.intel.com>

It looks much better than mine. and could replace 'mm/lru: introduce the relock_page_lruvec function'
with your author signed. :)

BTW,
it's the rcu_read_lock cause the will-it-scale/page_fault3 regression which you mentained in another
letter?

Thanks
Alex

在 2020/8/1 上午5:14, alexander.h.duyck@intel.com 写道:
> From: Alexander Duyck <alexander.h.duyck@linux.intel.com>
> 
> When testing for relock we can avoid the need for RCU locking if we simply
> compare the page pgdat and memcg pointers versus those that the lruvec is
> holding. By doing this we can avoid the extra pointer walks and accesses of
> the memory cgroup.
> 
> In addition we can avoid the checks entirely if lruvec is currently NULL.
> 
> Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
> ---
>  include/linux/memcontrol.h |   52 +++++++++++++++++++++++++++-----------------
>  1 file changed, 32 insertions(+), 20 deletions(-)
> 
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index 6e670f991b42..7a02f00bf3de 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -405,6 +405,22 @@ static inline struct lruvec *mem_cgroup_lruvec(struct mem_cgroup *memcg,
>  
>  struct lruvec *mem_cgroup_page_lruvec(struct page *, struct pglist_data *);
>  
> +static inline bool lruvec_holds_page_lru_lock(struct page *page,
> +					      struct lruvec *lruvec)
> +{
> +	pg_data_t *pgdat = page_pgdat(page);
> +	const struct mem_cgroup *memcg;
> +	struct mem_cgroup_per_node *mz;
> +
> +	if (mem_cgroup_disabled())
> +		return lruvec == &pgdat->__lruvec;
> +
> +	mz = container_of(lruvec, struct mem_cgroup_per_node, lruvec);
> +	memcg = page->mem_cgroup ? : root_mem_cgroup;
> +
> +	return lruvec->pgdat == pgdat && mz->memcg == memcg;
> +}
> +
>  struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p);
>  
>  struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm);
> @@ -880,6 +896,14 @@ static inline struct lruvec *mem_cgroup_page_lruvec(struct page *page,
>  	return &pgdat->__lruvec;
>  }
>  
> +static inline bool lruvec_holds_page_lru_lock(struct page *page,
> +					      struct lruvec *lruvec)
> +{
> +		pg_data_t *pgdat = page_pgdat(page);
> +
> +		return lruvec == &pgdat->__lruvec;
> +}
> +
>  static inline struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *memcg)
>  {
>  	return NULL;
> @@ -1317,18 +1341,12 @@ static inline void unlock_page_lruvec_irqrestore(struct lruvec *lruvec,
>  static inline struct lruvec *relock_page_lruvec_irq(struct page *page,
>  		struct lruvec *locked_lruvec)
>  {
> -	struct pglist_data *pgdat = page_pgdat(page);
> -	bool locked;
> +	if (locked_lruvec) {
> +		if (lruvec_holds_page_lru_lock(page, locked_lruvec))
> +			return locked_lruvec;
>  
> -	rcu_read_lock();
> -	locked = mem_cgroup_page_lruvec(page, pgdat) == locked_lruvec;
> -	rcu_read_unlock();
> -
> -	if (locked)
> -		return locked_lruvec;
> -
> -	if (locked_lruvec)
>  		unlock_page_lruvec_irq(locked_lruvec);
> +	}
>  
>  	return lock_page_lruvec_irq(page);
>  }
> @@ -1337,18 +1355,12 @@ static inline struct lruvec *relock_page_lruvec_irq(struct page *page,
>  static inline struct lruvec *relock_page_lruvec_irqsave(struct page *page,
>  		struct lruvec *locked_lruvec, unsigned long *flags)
>  {
> -	struct pglist_data *pgdat = page_pgdat(page);
> -	bool locked;
> -
> -	rcu_read_lock();
> -	locked = mem_cgroup_page_lruvec(page, pgdat) == locked_lruvec;
> -	rcu_read_unlock();
> -
> -	if (locked)
> -		return locked_lruvec;
> +	if (locked_lruvec) {
> +		if (lruvec_holds_page_lru_lock(page, locked_lruvec))
> +			return locked_lruvec;
>  
> -	if (locked_lruvec)
>  		unlock_page_lruvec_irqrestore(locked_lruvec, *flags);
> +	}
>  
>  	return lock_page_lruvec_irqsave(page, flags);
>  }
> 


  reply index

Thread overview: 102+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-25 12:59 [PATCH v17 00/21] per memcg lru lock Alex Shi
2020-07-25 12:59 ` [PATCH v17 01/21] mm/vmscan: remove unnecessary lruvec adding Alex Shi
2020-08-06  3:47   ` Alex Shi
2020-07-25 12:59 ` [PATCH v17 02/21] mm/page_idle: no unlikely double check for idle page counting Alex Shi
2020-07-25 12:59 ` [PATCH v17 03/21] mm/compaction: correct the comments of compact_defer_shift Alex Shi
2020-07-27 17:29   ` Alexander Duyck
2020-07-28 11:59     ` Alex Shi
2020-07-28 14:17       ` Alexander Duyck
2020-07-25 12:59 ` [PATCH v17 04/21] mm/compaction: rename compact_deferred as compact_should_defer Alex Shi
2020-07-25 12:59 ` [PATCH v17 05/21] mm/thp: move lru_add_page_tail func to huge_memory.c Alex Shi
2020-07-25 12:59 ` [PATCH v17 06/21] mm/thp: clean up lru_add_page_tail Alex Shi
2020-07-25 12:59 ` [PATCH v17 07/21] mm/thp: remove code path which never got into Alex Shi
2020-07-25 12:59 ` [PATCH v17 08/21] mm/thp: narrow lru locking Alex Shi
2020-07-25 12:59 ` [PATCH v17 09/21] mm/memcg: add debug checking in lock_page_memcg Alex Shi
2020-07-25 12:59 ` [PATCH v17 10/21] mm/swap: fold vm event PGROTATED into pagevec_move_tail_fn Alex Shi
2020-07-25 12:59 ` [PATCH v17 11/21] mm/lru: move lru_lock holding in func lru_note_cost_page Alex Shi
2020-08-05 21:18   ` Alexander Duyck
2020-07-25 12:59 ` [PATCH v17 12/21] mm/lru: move lock into lru_note_cost Alex Shi
2020-07-25 12:59 ` [PATCH v17 13/21] mm/lru: introduce TestClearPageLRU Alex Shi
2020-07-29  3:53   ` Alex Shi
2020-08-05 22:43     ` Alexander Duyck
2020-08-06  1:54       ` Alex Shi
2020-08-06 14:41         ` Alexander Duyck
2020-07-25 12:59 ` [PATCH v17 14/21] mm/compaction: do page isolation first in compaction Alex Shi
2020-08-04 21:35   ` Alexander Duyck
2020-08-06 18:38   ` Alexander Duyck
2020-08-07  3:24     ` Alex Shi
2020-08-07 14:51       ` Alexander Duyck
2020-08-10 13:10         ` Alex Shi
2020-08-10 14:41           ` Alexander Duyck
2020-08-11  8:22             ` Alex Shi
2020-08-11 14:47               ` Alexander Duyck
2020-08-12 11:43                 ` Alex Shi
2020-08-12 12:16                   ` Alex Shi
2020-08-12 16:51                   ` Alexander Duyck
2020-08-13  1:46                     ` Alex Shi
2020-08-13  2:17                       ` Alexander Duyck
2020-08-13  3:52                         ` Alex Shi
2020-08-13  4:02                       ` [RFC PATCH 0/3] " Alexander Duyck
2020-08-13  4:02                         ` [RFC PATCH 1/3] mm: Drop locked from isolate_migratepages_block Alexander Duyck
2020-08-13  6:56                           ` Alex Shi
2020-08-13 14:32                             ` Alexander Duyck
2020-08-14  7:25                               ` Alex Shi
2020-08-13  7:44                           ` Alex Shi
2020-08-13 14:26                             ` Alexander Duyck
2020-08-13  4:02                         ` [RFC PATCH 2/3] mm: Drop use of test_and_set_skip in favor of just setting skip Alexander Duyck
2020-08-14  7:19                           ` Alex Shi
2020-08-14 14:24                             ` Alexander Duyck
2020-08-14 21:15                               ` Alexander Duyck
2020-08-15  9:49                                 ` Alex Shi
2020-08-17 15:38                                   ` Alexander Duyck
2020-08-18  6:50                           ` Alex Shi
2020-08-13  4:02                         ` [RFC PATCH 3/3] mm: Identify compound pages sooner in isolate_migratepages_block Alexander Duyck
2020-08-14  7:20                           ` Alex Shi
2020-08-17 22:58   ` [PATCH v17 14/21] mm/compaction: do page isolation first in compaction Alexander Duyck
2020-07-25 12:59 ` [PATCH v17 15/21] mm/thp: add tail pages into lru anyway in split_huge_page() Alex Shi
2020-07-25 12:59 ` [PATCH v17 16/21] mm/swap: serialize memcg changes in pagevec_lru_move_fn Alex Shi
2020-07-25 12:59 ` [PATCH v17 17/21] mm/lru: replace pgdat lru_lock with lruvec lock Alex Shi
2020-07-27 23:34   ` Alexander Duyck
2020-07-28  7:15     ` Alex Shi
2020-07-28 11:19     ` Alex Shi
2020-07-28 14:54       ` Alexander Duyck
2020-07-29  1:00         ` Alex Shi
2020-07-29  1:27           ` Alexander Duyck
2020-07-29  2:27             ` Alex Shi
2020-07-28 15:39     ` Alex Shi
2020-07-28 15:55       ` Alexander Duyck
2020-07-29  0:48         ` Alex Shi
2020-07-29  3:54   ` Alex Shi
2020-08-06  7:41   ` Alex Shi
2020-07-25 12:59 ` [PATCH v17 18/21] mm/lru: introduce the relock_page_lruvec function Alex Shi
2020-07-29 17:52   ` Alexander Duyck
2020-07-30  6:08     ` Alex Shi
2020-07-31 14:20       ` Alexander Duyck
2020-07-31 21:14   ` [PATCH RFC] mm: Add function for testing if the current lruvec lock is valid alexander.h.duyck
2020-07-31 23:54     ` Alex Shi [this message]
2020-08-02 18:20       ` Alexander Duyck
2020-08-04  6:13         ` Alex Shi
2020-07-25 12:59 ` [PATCH v17 19/21] mm/vmscan: use relock for move_pages_to_lru Alex Shi
2020-08-03 22:49   ` Alexander Duyck
2020-08-04  6:23     ` Alex Shi
2020-07-25 12:59 ` [PATCH v17 20/21] mm/pgdat: remove pgdat lru_lock Alex Shi
2020-08-03 22:42   ` Alexander Duyck
2020-08-03 22:45     ` Alexander Duyck
2020-08-04  6:22       ` Alex Shi
2020-07-25 12:59 ` [PATCH v17 21/21] mm/lru: revise the comments of lru_lock Alex Shi
2020-08-03 22:37   ` Alexander Duyck
2020-08-04 10:04     ` Alex Shi
2020-08-04 14:29       ` Alexander Duyck
2020-08-06  1:39         ` Alex Shi
2020-08-06 16:27           ` Alexander Duyck
2020-07-27  5:40 ` [PATCH v17 00/21] per memcg lru lock Alex Shi
2020-07-29 14:49   ` Alex Shi
2020-07-29 18:06     ` Hugh Dickins
2020-07-30  2:16       ` Alex Shi
2020-08-03 15:07         ` Michal Hocko
2020-08-04  6:14           ` Alex Shi
2020-07-31 21:31 ` Alexander Duyck
2020-08-04  8:36 ` Alex Shi
2020-08-04  8:36 ` Alex Shi
2020-08-04  8:37 ` Alex Shi
2020-08-04  8:37 ` Alex Shi

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