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From: Joao Martins <joao.m.martins@oracle.com>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Linux MM <linux-mm@kvack.org>,
	linux-nvdimm <linux-nvdimm@lists.01.org>,
	Matthew Wilcox <willy@infradead.org>,
	Jason Gunthorpe <jgg@ziepe.ca>,
	Muchun Song <songmuchun@bytedance.com>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	John Hubbard <jhubbard@nvidia.com>
Subject: Re: [PATCH RFC 1/9] memremap: add ZONE_DEVICE support for compound pages
Date: Tue, 23 Feb 2021 17:18:20 +0000	[thread overview]
Message-ID: <e9e24d05-79e7-275a-530d-fc3b5041845d@oracle.com> (raw)
In-Reply-To: <CAPcyv4gsVWi8j=aZj3n1-O=39gq2jULcpWgiY22U6hpGTpcGzA@mail.gmail.com>

On 2/23/21 4:50 PM, Dan Williams wrote:
> On Tue, Feb 23, 2021 at 7:46 AM Joao Martins <joao.m.martins@oracle.com> wrote:
>> On 2/22/21 8:37 PM, Dan Williams wrote:
>>> On Mon, Feb 22, 2021 at 3:24 AM Joao Martins <joao.m.martins@oracle.com> wrote:
>>>> On 2/20/21 1:43 AM, Dan Williams wrote:
>>>>> On Tue, Dec 8, 2020 at 9:59 PM John Hubbard <jhubbard@nvidia.com> wrote:
>>>>>> On 12/8/20 9:28 AM, Joao Martins wrote:

[...]

>>> Don't get me wrong the
>>> capability is still needed for filesystem-dax, but the distinction is
>>> that vmemmap_populate_compound_pages() need never worry about an
>>> altmap.
>>>
>> IMO there's not much added complexity strictly speaking about altmap. We still use the
>> same vmemmap_{pmd,pte,pgd}_populate helpers which just pass an altmap. So whatever it is
>> being maintained for fsdax or other altmap consumers (e.g. we seem to be working towards
>> hotplug making use of it) we are using it in the exact same way.
>>
>> The complexity of the future vmemmap_populate_compound_pages() has more to do with reusing
>> vmemmap blocks allocated in previous vmemmap pages, and preserving that across section
>> onlining (for 1G pages).
> 
> True, I'm less worried about the complexity as much as
> opportunistically converting configurations to RAM backed pages. It's
> already the case that poison handling is page mapping size aligned for
> device-dax, and filesystem-dax needs to stick with non-compound-pages
> for the foreseeable future.
> 
Hmm, I was sort off wondering that fsdax could move to compound pages too as
opposed to base pages, albeit not necessarily using the vmemmap page reuse
as it splits pages IIUC.

> Ok, let's try to keep altmap in vmemmap_populate_compound_pages() and
> see how it looks.
> 
OK, will do.
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  reply	other threads:[~2021-02-23 17:18 UTC|newest]

Thread overview: 67+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-08 17:28 [PATCH RFC 0/9] mm, sparse-vmemmap: Introduce compound pagemaps Joao Martins
2020-12-08 17:28 ` [PATCH RFC 1/9] memremap: add ZONE_DEVICE support for compound pages Joao Martins
2020-12-09  5:59   ` John Hubbard
2020-12-09  6:33     ` Matthew Wilcox
2020-12-09 13:12       ` Joao Martins
2021-02-20  1:43     ` Dan Williams
2021-02-22 11:24       ` Joao Martins
2021-02-22 20:37         ` Dan Williams
2021-02-23 15:46           ` Joao Martins
2021-02-23 16:50             ` Dan Williams
2021-02-23 17:18               ` Joao Martins [this message]
2021-02-23 18:18                 ` Dan Williams
2021-03-10 18:12           ` Joao Martins
2021-03-12  5:54             ` Dan Williams
2021-02-20  1:24   ` Dan Williams
2021-02-22 11:09     ` Joao Martins
2020-12-08 17:28 ` [PATCH RFC 2/9] sparse-vmemmap: Consolidate arguments in vmemmap section populate Joao Martins
2020-12-09  6:16   ` John Hubbard
2020-12-09 13:51     ` Joao Martins
2021-02-20  1:49   ` Dan Williams
2021-02-22 11:26     ` Joao Martins
2020-12-08 17:28 ` [PATCH RFC 3/9] sparse-vmemmap: Reuse vmemmap areas for a given mhp_params::align Joao Martins
2020-12-08 17:38   ` Joao Martins
2020-12-08 17:28 ` [PATCH RFC 3/9] sparse-vmemmap: Reuse vmemmap areas for a given page size Joao Martins
2021-02-20  3:34   ` Dan Williams
2021-02-22 11:42     ` Joao Martins
2021-02-22 22:40       ` Dan Williams
2021-02-23 15:46         ` Joao Martins
2020-12-08 17:28 ` [PATCH RFC 4/9] mm/page_alloc: Reuse tail struct pages for compound pagemaps Joao Martins
2021-02-20  6:17   ` Dan Williams
2021-02-22 12:01     ` Joao Martins
2020-12-08 17:28 ` [PATCH RFC 5/9] device-dax: Compound pagemap support Joao Martins
2020-12-08 17:28 ` [PATCH RFC 6/9] mm/gup: Grab head page refcount once for group of subpages Joao Martins
2020-12-09  4:40   ` John Hubbard
2020-12-09 13:44     ` Joao Martins
     [not found]   ` <20201208194905.GQ5487@ziepe.ca>
2020-12-09 11:05     ` Joao Martins
     [not found]       ` <20201209151505.GV5487@ziepe.ca>
2020-12-09 16:02         ` Joao Martins
     [not found]           ` <20201209162438.GW5487@ziepe.ca>
2020-12-09 17:27             ` Joao Martins
2020-12-09 18:14             ` Matthew Wilcox
2020-12-10 15:43               ` Joao Martins
2020-12-08 17:28 ` [PATCH RFC 7/9] mm/gup: Decrement head page " Joao Martins
     [not found]   ` <20201208193446.GP5487@ziepe.ca>
2020-12-09  5:06     ` John Hubbard
2020-12-09 12:17     ` Joao Martins
2020-12-17 19:05     ` Joao Martins
     [not found]       ` <20201217200530.GK5487@ziepe.ca>
2020-12-17 22:34         ` Joao Martins
2020-12-19  2:06         ` John Hubbard
2020-12-19 13:10           ` Joao Martins
2020-12-08 17:29 ` [PATCH RFC 8/9] RDMA/umem: batch page unpin in __ib_mem_release() Joao Martins
2020-12-09  5:18   ` John Hubbard
     [not found]   ` <20201208192935.GA1908088@ziepe.ca>
2020-12-09 10:59     ` Joao Martins
2020-12-19 13:15       ` Joao Martins
2020-12-08 17:29 ` [PATCH RFC 9/9] mm: Add follow_devmap_page() for devdax vmas Joao Martins
2020-12-09  5:23   ` John Hubbard
     [not found]   ` <20201208195754.GR5487@ziepe.ca>
2020-12-09  8:05     ` Christoph Hellwig
2020-12-09 11:19     ` Joao Martins
2020-12-09  9:38 ` [PATCH RFC 0/9] mm, sparse-vmemmap: Introduce compound pagemaps David Hildenbrand
2020-12-09  9:52 ` [External] " Muchun Song
2021-02-20  1:18 ` Dan Williams
2021-02-22 11:06   ` Joao Martins
2021-02-22 14:32     ` Joao Martins
2021-02-23 16:28   ` Joao Martins
2021-02-23 16:44     ` Dan Williams
2021-02-23 17:15       ` Joao Martins
2021-02-23 18:15         ` Dan Williams
     [not found]       ` <20210223185435.GO2643399@ziepe.ca>
2021-02-23 22:48         ` Dan Williams
     [not found]           ` <20210223230723.GP2643399@ziepe.ca>
2021-02-24  0:14             ` Dan Williams
     [not found]               ` <20210224010017.GQ2643399@ziepe.ca>
2021-02-24  1:32                 ` Dan Williams

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