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From: Joao Martins <joao.m.martins@oracle.com>
To: Muchun Song <songmuchun@bytedance.com>
Cc: Linux Memory Management List <linux-mm@kvack.org>,
	Dan Williams <dan.j.williams@intel.com>,
	Vishal Verma <vishal.l.verma@intel.com>,
	Matthew Wilcox <willy@infradead.org>,
	Jason Gunthorpe <jgg@ziepe.ca>, Jane Chu <jane.chu@oracle.com>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Jonathan Corbet <corbet@lwn.net>, Christoph Hellwig <hch@lst.de>,
	nvdimm@lists.linux.dev,
	Linux Doc Mailing List <linux-doc@vger.kernel.org>
Subject: Re: [PATCH v5 4/5] mm/sparse-vmemmap: improve memory savings for compound devmaps
Date: Mon, 14 Feb 2022 10:57:15 +0000	[thread overview]
Message-ID: <23cd2843-9494-c129-4038-b23a16ecb0a9@oracle.com> (raw)
In-Reply-To: <CAMZfGtUSxtnrY3Vkn8gP2T2jUjWdfVXu7+zt5Ny4VBi7ZDkWAg@mail.gmail.com>

On 2/12/22 14:49, Muchun Song wrote:
> On Sat, Feb 12, 2022 at 6:08 PM Muchun Song <songmuchun@bytedance.com> wrote:
>> On Fri, Feb 11, 2022 at 8:37 PM Joao Martins <joao.m.martins@oracle.com> wrote:
>>> On 2/11/22 07:54, Muchun Song wrote:
>>>> On Fri, Feb 11, 2022 at 3:34 AM Joao Martins <joao.m.martins@oracle.com> wrote:
>>>>> -       if (vmemmap_populate(start, end, nid, altmap))
>>>>> +       if (pgmap && pgmap_vmemmap_nr(pgmap) > 1 && !altmap)
>>>>
>>>> Should we add a judgment like "is_power_of_2(sizeof(struct page))" since
>>>> this optimization is only applied when the size of the struct page does not
>>>> cross page boundaries?
>>>
>>> Totally miss that -- let me make that adjustment.
>>>
>>> Can I ask which architectures/conditions this happens?
>>
>> E.g. arm64 when !CONFIG_MEMCG.
> 
> Plus !CONFIG_SLUB even on x86_64.

Oh, thanks for the ref -- hadn't realized that this was
possible on arm64/x86.


  reply	other threads:[~2022-02-14 10:57 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-10 19:33 [PATCH v5 0/5] sparse-vmemmap: memory savings for compound devmaps (device-dax) Joao Martins
2022-02-10 19:33 ` [PATCH v5 1/5] mm/sparse-vmemmap: add a pgmap argument to section activation Joao Martins
2022-02-11  8:03   ` Muchun Song
2022-02-11 12:37     ` Joao Martins
2022-02-10 19:33 ` [PATCH v5 2/5] mm/sparse-vmemmap: refactor core of vmemmap_populate_basepages() to helper Joao Martins
2022-02-11  7:54   ` Muchun Song
2022-02-10 19:33 ` [PATCH v5 3/5] mm/hugetlb_vmemmap: move comment block to Documentation/vm Joao Martins
2022-02-10 19:33 ` [PATCH v5 4/5] mm/sparse-vmemmap: improve memory savings for compound devmaps Joao Martins
2022-02-11  7:54   ` Muchun Song
2022-02-11 12:37     ` Joao Martins
2022-02-12 10:08       ` Muchun Song
2022-02-12 14:49         ` Muchun Song
2022-02-14 10:57           ` Joao Martins [this message]
2022-02-14 10:55         ` Joao Martins
2022-02-10 19:33 ` [PATCH v5 5/5] mm/page_alloc: reuse tail struct pages " Joao Martins
2022-02-11  5:07   ` Muchun Song
2022-02-11 12:48     ` Joao Martins
2022-02-12 11:11       ` Muchun Song

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