From: Alex Shi <alex.shi@linux.alibaba.com>
To: Alexander Duyck <alexander.duyck@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Mel Gorman <mgorman@techsingularity.net>,
Tejun Heo <tj@kernel.org>, Hugh Dickins <hughd@google.com>,
Konstantin Khlebnikov <khlebnikov@yandex-team.ru>,
Daniel Jordan <daniel.m.jordan@oracle.com>,
Yang Shi <yang.shi@linux.alibaba.com>,
Matthew Wilcox <willy@infradead.org>,
Johannes Weiner <hannes@cmpxchg.org>,
kbuild test robot <lkp@intel.com>, linux-mm <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
cgroups@vger.kernel.org, Shakeel Butt <shakeelb@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Wei Yang <richard.weiyang@gmail.com>,
"Kirill A. Shutemov" <kirill@shutemov.name>,
Rong Chen <rong.a.chen@intel.com>,
Andrey Ryabinin <aryabinin@virtuozzo.com>,
Jann Horn <jannh@google.com>
Subject: Re: [PATCH v17 21/21] mm/lru: revise the comments of lru_lock
Date: Thu, 6 Aug 2020 09:39:12 +0800 [thread overview]
Message-ID: <a1c6a3a6-f8e3-7bb5-e881-216a4b57ae84@linux.alibaba.com> (raw)
In-Reply-To: <CAKgT0UckqbmYJDE3L2Bg1Nr=Y=GT0OBx1GEhaZ14EbRTzd8tiw@mail.gmail.com>
在 2020/8/4 下午10:29, Alexander Duyck 写道:
> On Tue, Aug 4, 2020 at 3:04 AM Alex Shi <alex.shi@linux.alibaba.com> wrote:
>>
>>
>>
>> 在 2020/8/4 上午6:37, Alexander Duyck 写道:
>>>>
>>>> shrink_inactive_list() also diverts any unevictable pages that it finds on the
>>>> -inactive lists to the appropriate zone's unevictable list.
>>>> +inactive lists to the appropriate node's unevictable list.
>>>>
>>>> shrink_inactive_list() should only see SHM_LOCK'd pages that became SHM_LOCK'd
>>>> after shrink_active_list() had moved them to the inactive list, or pages mapped
>>> Same here.
>>
>> lruvec is used per memcg per node actually, and it fallback to node if memcg disabled.
>> So the comments are still right.
>>
>> And most of changes just fix from zone->lru_lock to pgdat->lru_lock change.
>
> Actually in my mind one thing that might work better would be to
> explain what the lruvec is and where it resides. Then replace zone
> with lruvec since that is really where the unevictable list resides.
> Then it would be correct for both the memcg and pgdat case.
Could you like to revise the doc as your thought?
>
>>>
>>>> diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
>>>> index 64ede5f150dc..44738cdb5a55 100644
>>>> --- a/include/linux/mm_types.h
>>>> +++ b/include/linux/mm_types.h
>>>> @@ -78,7 +78,7 @@ struct page {
>>>> struct { /* Page cache and anonymous pages */
>>>> /**
>>>> * @lru: Pageout list, eg. active_list protected by
>>>> - * pgdat->lru_lock. Sometimes used as a generic list
>>>> + * lruvec->lru_lock. Sometimes used as a generic list
>>>> * by the page owner.
>>>> */
>>>> struct list_head lru;
>>>> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
>>>> index 8af956aa13cf..c92289a4e14d 100644
>>>> --- a/include/linux/mmzone.h
>>>> +++ b/include/linux/mmzone.h
>>>> @@ -115,7 +115,7 @@ static inline bool free_area_empty(struct free_area *area, int migratetype)
>>>> struct pglist_data;
>>>>
>>>> /*
>>>> - * zone->lock and the zone lru_lock are two of the hottest locks in the kernel.
>>>> + * zone->lock and the lru_lock are two of the hottest locks in the kernel.
>>>> * So add a wild amount of padding here to ensure that they fall into separate
>>>> * cachelines. There are very few zone structures in the machine, so space
>>>> * consumption is not a concern here.
>>> So I don't believe you are using ZONE_PADDING in any way to try and
>>> protect the LRU lock currently. At least you aren't using it in the
>>> lruvec. As such it might make sense to just drop the reference to the
>>> lru_lock here. That reminds me that we still need to review the
>>> placement of the lru_lock and determine if there might be a better
>>> placement and/or padding that might improve performance when under
>>> heavy stress.
>>>
>>
>> Right, is it the following looks better?
>>
>> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
>> index ccc76590f823..0ed520954843 100644
>> --- a/include/linux/mmzone.h
>> +++ b/include/linux/mmzone.h
>> @@ -113,8 +113,7 @@ static inline bool free_area_empty(struct free_area *area, int migratetype)
>> struct pglist_data;
>>
>> /*
>> - * zone->lock and the lru_lock are two of the hottest locks in the kernel.
>> - * So add a wild amount of padding here to ensure that they fall into separate
>> + * Add a wild amount of padding here to ensure datas fall into separate
>> * cachelines. There are very few zone structures in the machine, so space
>> * consumption is not a concern here.
>> */
>>
>> Thanks!
>> Alex
>
> I would maybe tweak it to make sure it is clear that we are using this
> to pad out items that are likely to cause cache thrash such as various
> hot spinocks and such.
>
I appreciate if you like to change the doc better. :)
Thanks
Alex
next prev parent reply other threads:[~2020-08-06 1:39 UTC|newest]
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
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 [this message]
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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