Re: [LSF/MM/BPF TOPIC] State Of The Page

From: Gao Xiang <hsiangkao@linux.alibaba.com>
To: Yang Shi <shy828301@gmail.com>, Mel Gorman <mgorman@techsingularity.net>
Cc: Matthew Wilcox <willy@infradead.org>,
	lsf-pc@lists.linux-foundation.org, linux-fsdevel@vger.kernel.org,
	linux-mm@kvack.org, linux-block@vger.kernel.org,
	linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org,
	linux-nvme@lists.infradead.org, bpf@vger.kernel.org
Subject: Re: [LSF/MM/BPF TOPIC] State Of The Page
Date: Wed, 22 Feb 2023 10:40:09 +0800	[thread overview]
Message-ID: <a328da48-a5aa-c31b-074c-d52132997afd@linux.alibaba.com> (raw)
In-Reply-To: <CAHbLzkqsyv6rw-RRvNcB0PoEE75qS9ZtmywhJYZbVA05d5tj5A@mail.gmail.com>

On 2023/2/22 03:09, Yang Shi wrote:
> On Tue, Feb 21, 2023 at 10:08 AM Gao Xiang <hsiangkao@linux.alibaba.com> wrote:
>>
>>
>>
>> On 2023/1/27 00:40, Matthew Wilcox wrote:
>>> I'd like to do another session on how the struct page dismemberment
>>> is going and what remains to be done.  Given how widely struct page is
>>> used, I think there will be interest from more than just MM, so I'd
>>> suggest a plenary session.
>>>
>>> If I were hosting this session today, topics would include:
>>>
>>> Splitting out users:
>>>
>>>    - slab (done!)
>>>    - netmem (in progress)
>>>    - hugetlb (in akpm)
>>>    - tail pages (in akpm)
>>>    - page tables
>>>    - ZONE_DEVICE
>>>
>>> Users that really should have their own types:
>>>
>>>    - zsmalloc
>>>    - bootmem
>>>    - percpu
>>>    - buddy
>>>    - vmalloc
>>>
>>> Converting filesystems to folios:
>>>
>>>    - XFS (done)
>>>    - AFS (done)
>>>    - NFS (in progress)
>>>    - ext4 (in progress)
>>>    - f2fs (in progress)
>>>    - ... others?
>>>
>>> Unresolved challenges:
>>>
>>>    - mapcount
>>>    - AnonExclusive
>>>    - Splitting anon & file folios apart
>>>    - Removing PG_error & PG_private
>>
>> I'm interested in this topic too, also I'd like to get some idea of the
>> future of the page dismemberment timeline so that I can have time to keep
>> the pace with it since some embedded use cases like Android are
>> memory-sensitive all the time.
>>
>> Minor, it seems some apis still use ->lru field to chain bulk pages,
>> perhaps it needs some changes as well:
>> https://lore.kernel.org/r/20221222124412.rpnl2vojnx7izoow@techsingularity.net
>> https://lore.kernel.org/r/20230214190221.1156876-2-shy828301@gmail.com
> 
> The dm-crypt patches don't use list anymore. The bulk allocator still
> supports the list version, but so far there is no user, so it may be
> gone soon.

Thanks, it's just a detailed minor stuff relating to page->lru.  Currently
I'm no rush to evaluate/use it.

> 
>>
>> Thanks,
>> Gao Xiang
>>
>>>
>>> This will probably all change before May.
>>>
>>> I'd like to nominate Vishal Moola & Sidhartha Kumar as invitees based on
>>> their work to convert various functions from pages to folios.
>>