From: Joao Martins <joao.m.martins@oracle.com>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Linux MM <linux-mm@kvack.org>,
Vishal Verma <vishal.l.verma@intel.com>,
Dave Jiang <dave.jiang@intel.com>,
Naoya Horiguchi <naoya.horiguchi@nec.com>,
Matthew Wilcox <willy@infradead.org>,
Jason Gunthorpe <jgg@ziepe.ca>,
John Hubbard <jhubbard@nvidia.com>,
Jane Chu <jane.chu@oracle.com>,
Muchun Song <songmuchun@bytedance.com>,
Mike Kravetz <mike.kravetz@oracle.com>,
Andrew Morton <akpm@linux-foundation.org>,
Jonathan Corbet <corbet@lwn.net>,
Linux NVDIMM <nvdimm@lists.linux.dev>,
Linux Doc Mailing List <linux-doc@vger.kernel.org>
Subject: Re: [PATCH v3 04/14] mm/memremap: add ZONE_DEVICE support for compound pages
Date: Thu, 15 Jul 2021 14:06:44 +0100 [thread overview]
Message-ID: <8a85d09a-be11-8016-0a59-bd622a98e335@oracle.com> (raw)
In-Reply-To: <d73793a8-7540-c473-0e30-0880341c2baf@oracle.com>
On 7/15/21 1:52 PM, Joao Martins wrote:
> On 7/15/21 2:08 AM, Dan Williams wrote:
>> On Wed, Jul 14, 2021 at 12:36 PM Joao Martins <joao.m.martins@oracle.com> wrote:
>>> instead of
>>> base pages. When a compound page geometry is requested, all but the first
>>> page are initialised as tail pages instead of order-0 pages.
>>>
>>> For certain ZONE_DEVICE users like device-dax which have a fixed page size,
>>> this creates an opportunity to optimize GUP and GUP-fast walkers, treating
>>> it the same way as THP or hugetlb pages.
>>>
>>> Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
>>> ---
>>> include/linux/memremap.h | 17 +++++++++++++++++
>>> mm/memremap.c | 8 ++++++--
>>> mm/page_alloc.c | 34 +++++++++++++++++++++++++++++++++-
>>> 3 files changed, 56 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/include/linux/memremap.h b/include/linux/memremap.h
>>> index 119f130ef8f1..e5ab6d4525c1 100644
>>> --- a/include/linux/memremap.h
>>> +++ b/include/linux/memremap.h
>>> @@ -99,6 +99,10 @@ struct dev_pagemap_ops {
>>> * @done: completion for @internal_ref
>>> * @type: memory type: see MEMORY_* in memory_hotplug.h
>>> * @flags: PGMAP_* flags to specify defailed behavior
>>> + * @geometry: structural definition of how the vmemmap metadata is populated.
>>> + * A zero or PAGE_SIZE defaults to using base pages as the memmap metadata
>>> + * representation. A bigger value but also multiple of PAGE_SIZE will set
>>> + * up compound struct pages representative of the requested geometry size.
>>> * @ops: method table
>>> * @owner: an opaque pointer identifying the entity that manages this
>>> * instance. Used by various helpers to make sure that no
>>> @@ -114,6 +118,7 @@ struct dev_pagemap {
>>> struct completion done;
>>> enum memory_type type;
>>> unsigned int flags;
>>> + unsigned long geometry;
>>> const struct dev_pagemap_ops *ops;
>>> void *owner;
>>> int nr_range;
>>> @@ -130,6 +135,18 @@ static inline struct vmem_altmap *pgmap_altmap(struct dev_pagemap *pgmap)
>>> return NULL;
>>> }
>>>
>>> +static inline unsigned long pgmap_geometry(struct dev_pagemap *pgmap)
>>> +{
>>> + if (!pgmap || !pgmap->geometry)
>>> + return PAGE_SIZE;
>>> + return pgmap->geometry;
>>> +}
>>> +
>>> +static inline unsigned long pgmap_pfn_geometry(struct dev_pagemap *pgmap)
>>> +{
>>> + return PHYS_PFN(pgmap_geometry(pgmap));
>>> +}
>>
>> Are both needed? Maybe just have ->geometry natively be in nr_pages
>> units directly, because pgmap_pfn_geometry() makes it confusing
>> whether it's a geometry of the pfn or the geometry of the pgmap.
>>
> I use pgmap_geometry() largelly when we manipulate memmap in sparse-vmemmap code, as we
> deal with addresses/offsets/subsection-size. While using pgmap_pfn_geometry for code that
> deals with PFN initialization. For this patch I could remove the confusion.
>
> And actually maybe I can just store the pgmap_geometry() value in bytes locally in
> vmemmap_populate_compound_pages() and we can remove this extra helper.
>
But one nice property of pgmap_geometry() is the @pgmap check and not needing that the
driver initializes a pgmap->geometry property. So a zeroed value would still support pgmap
users on the old case where there's no @geometry (or the user doesn't care). So departing
from this helper might mean that either memremap_pages() sets the right @geometry if a
zeroed value is passed in. and __populate_section_memmap() makes sures pgmap is associated
when trying to figure out if there's a geometry to consider in the section mapping.
next prev parent reply other threads:[~2021-07-15 13:07 UTC|newest]
Thread overview: 78+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-14 19:35 [PATCH v3 00/14] mm, sparse-vmemmap: Introduce compound pagemaps Joao Martins
2021-07-14 19:35 ` [PATCH v3 01/14] memory-failure: fetch compound_head after pgmap_pfn_valid() Joao Martins
2021-07-15 0:17 ` Dan Williams
2021-07-15 2:51 ` [External] " Muchun Song
2021-07-15 6:40 ` Christoph Hellwig
2021-07-15 9:19 ` Muchun Song
2021-07-15 13:17 ` Joao Martins
2021-07-14 19:35 ` [PATCH v3 02/14] mm/page_alloc: split prep_compound_page into head and tail subparts Joao Martins
2021-07-15 0:19 ` Dan Williams
2021-07-15 2:53 ` [External] " Muchun Song
2021-07-15 13:17 ` Joao Martins
2021-07-14 19:35 ` [PATCH v3 03/14] mm/page_alloc: refactor memmap_init_zone_device() page init Joao Martins
2021-07-15 0:20 ` Dan Williams
2021-07-14 19:35 ` [PATCH v3 04/14] mm/memremap: add ZONE_DEVICE support for compound pages Joao Martins
2021-07-15 1:08 ` Dan Williams
2021-07-15 12:52 ` Joao Martins
2021-07-15 13:06 ` Joao Martins [this message]
2021-07-15 19:48 ` Dan Williams
2021-07-30 16:13 ` Joao Martins
2021-07-22 0:38 ` Jane Chu
2021-07-22 10:56 ` Joao Martins
2021-07-15 12:59 ` Christoph Hellwig
2021-07-15 13:15 ` Joao Martins
2021-07-15 6:48 ` Christoph Hellwig
2021-07-15 13:15 ` Joao Martins
2021-07-14 19:35 ` [PATCH v3 05/14] mm/sparse-vmemmap: add a pgmap argument to section activation Joao Martins
2021-07-28 5:56 ` Dan Williams
2021-07-28 9:43 ` Joao Martins
2021-07-14 19:35 ` [PATCH v3 06/14] mm/sparse-vmemmap: refactor core of vmemmap_populate_basepages() to helper Joao Martins
2021-07-28 6:04 ` Dan Williams
2021-07-28 10:48 ` Joao Martins
2021-07-14 19:35 ` [PATCH v3 07/14] mm/hugetlb_vmemmap: move comment block to Documentation/vm Joao Martins
2021-07-15 2:47 ` [External] " Muchun Song
2021-07-15 13:16 ` Joao Martins
2021-07-28 6:09 ` Dan Williams
2021-07-14 19:35 ` [PATCH v3 08/14] mm/sparse-vmemmap: populate compound pagemaps Joao Martins
2021-07-28 6:55 ` Dan Williams
2021-07-28 15:35 ` Joao Martins
2021-07-28 18:03 ` Dan Williams
2021-07-28 18:54 ` Joao Martins
2021-07-28 20:04 ` Joao Martins
2021-07-14 19:35 ` [PATCH v3 09/14] mm/page_alloc: reuse tail struct pages for " Joao Martins
2021-07-28 7:28 ` Dan Williams
2021-07-28 15:56 ` Joao Martins
2021-07-28 16:08 ` Dan Williams
2021-07-28 16:12 ` Joao Martins
2021-07-14 19:35 ` [PATCH v3 10/14] device-dax: use ALIGN() for determining pgoff Joao Martins
2021-07-28 7:29 ` Dan Williams
2021-07-28 15:56 ` Joao Martins
2021-07-14 19:35 ` [PATCH v3 11/14] device-dax: ensure dev_dax->pgmap is valid for dynamic devices Joao Martins
2021-07-28 7:30 ` Dan Williams
2021-07-28 15:56 ` Joao Martins
2021-08-06 12:28 ` Joao Martins
2021-07-14 19:35 ` [PATCH v3 12/14] device-dax: compound pagemap support Joao Martins
2021-07-14 23:36 ` Dan Williams
2021-07-15 12:00 ` Joao Martins
2021-07-27 23:51 ` Dan Williams
2021-07-28 9:36 ` Joao Martins
2021-07-28 18:51 ` Dan Williams
2021-07-28 18:59 ` Joao Martins
2021-07-28 19:03 ` Dan Williams
2021-07-14 19:35 ` [PATCH v3 13/14] mm/gup: grab head page refcount once for group of subpages Joao Martins
2021-07-28 19:55 ` Dan Williams
2021-07-28 20:07 ` Joao Martins
2021-07-28 20:23 ` Dan Williams
2021-08-25 19:10 ` Joao Martins
2021-08-25 19:15 ` Matthew Wilcox
2021-08-25 19:26 ` Joao Martins
2021-07-14 19:35 ` [PATCH v3 14/14] mm/sparse-vmemmap: improve memory savings for compound pud geometry Joao Martins
2021-07-28 20:03 ` Dan Williams
2021-07-28 20:08 ` Joao Martins
2021-07-14 21:48 ` [PATCH v3 00/14] mm, sparse-vmemmap: Introduce compound pagemaps Andrew Morton
2021-07-14 23:47 ` Dan Williams
2021-07-22 2:24 ` Matthew Wilcox
2021-07-22 10:53 ` Joao Martins
2021-07-27 23:23 ` Dan Williams
2021-08-02 10:40 ` Joao Martins
2021-08-02 14:06 ` Dan Williams
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