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> Subject: Re: [PATCH RFC 0/9] mm, sparse-vmemmap: Introduce compound pagemaps Date: Tue, 23 Feb 2021 17:15:04 +0000 [thread overview] Message-ID: <1cf0adb0-9692-bcb2-4d3d-374ba3164994@oracle.com> (raw) In-Reply-To: <CAPcyv4joomjhZYaCBNrYjvATSYgECfHYOZy=n_QVKqX7D_ReZQ@mail.gmail.com> On 2/23/21 4:44 PM, Dan Williams wrote: > On Tue, Feb 23, 2021 at 8:30 AM Joao Martins <joao.m.martins@oracle.com> wrote: >> >> On 2/20/21 1:18 AM, Dan Williams wrote: >>> On Tue, Dec 8, 2020 at 9:32 AM Joao Martins <joao.m.martins@oracle.com> wrote: >>>> Patch 6 - 8: Optimize grabbing/release a page refcount changes given that we >>>> are working with compound pages i.e. we do 1 increment/decrement to the head >>>> page for a given set of N subpages compared as opposed to N individual writes. >>>> {get,pin}_user_pages_fast() for zone_device with compound pagemap consequently >>>> improves considerably, and unpin_user_pages() improves as well when passed a >>>> set of consecutive pages: >>>> >>>> before after >>>> (get_user_pages_fast 1G;2M page size) ~75k us -> ~3.2k ; ~5.2k us >>>> (pin_user_pages_fast 1G;2M page size) ~125k us -> ~3.4k ; ~5.5k us >>> >>> Compelling! >>> >> >> BTW is there any reason why we don't support pin_user_pages_fast() with FOLL_LONGTERM for >> device-dax? >> > > Good catch. > > Must have been an oversight of the conversion. FOLL_LONGTERM collides > with filesystem operations, but not device-dax. hmmmm, fwiw, it was unilaterally disabled for any devmap pmd/pud in commit 7af75561e171 ("mm/gup: add FOLL_LONGTERM capability to GUP fast") and I must only assume that by "DAX pages" the submitter was only referring to fs-dax pages. > In fact that's the > motivation for device-dax in the first instance, no need to coordinate > runtime physical address layout changes because the device is > statically allocated. > /me nods >> Looking at the history, I understand that fsdax can't support it atm, but I am not sure >> that the same holds for device-dax. I have this small chunk (see below the scissors mark) >> which relaxes this for a pgmap of type MEMORY_DEVICE_GENERIC, albeit not sure if there is >> a fundamental issue for the other types that makes this an unwelcoming change. >> >> Joao >> >> --------------------->8--------------------- >> >> Subject: [PATCH] mm/gup: allow FOLL_LONGTERM pin-fast for >> MEMORY_DEVICE_GENERIC >> >> The downside would be one extra lookup in dev_pagemap tree >> for other pgmap->types (P2P, FSDAX, PRIVATE). But just one >> per gup-fast() call. > > I'd guess a dev_pagemap lookup is faster than a get_user_pages slow > path. It should be measurable that this change is at least as fast or > faster than falling back to the slow path, but it would be good to > measure. > But with the changes I am/will-be making I hope gup-fast and gup-slow will be as fast (for present pmd/puds ofc, as the fault makes it slower). I'll formally submit below patch, once I ran over the numbers. > Code changes look good to me. > Cool! Will add in the suggested change below. >> >> Signed-off-by: Joao Martins <joao.m.martins@oracle.com> >> --- >> include/linux/mm.h | 5 +++++ >> mm/gup.c | 24 +++++++++++++----------- >> 2 files changed, 18 insertions(+), 11 deletions(-) >> >> diff --git a/include/linux/mm.h b/include/linux/mm.h >> index 32f0c3986d4f..c89a049bbd7a 100644 >> --- a/include/linux/mm.h >> +++ b/include/linux/mm.h >> @@ -1171,6 +1171,11 @@ static inline bool is_pci_p2pdma_page(const struct page *page) >> page->pgmap->type == MEMORY_DEVICE_PCI_P2PDMA; >> } >> >> +static inline bool devmap_longterm_available(const struct dev_pagemap *pgmap) >> +{ > > I'd call this devmap_can_longterm(). > Ack. _______________________________________________ Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org To unsubscribe send an email to linux-nvdimm-leave@lists.01.org
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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>, Ira Weiny <ira.weiny@intel.com>, linux-nvdimm <linux-nvdimm@lists.01.org>, Matthew Wilcox <willy@infradead.org>, Jason Gunthorpe <jgg@ziepe.ca>, Jane Chu <jane.chu@oracle.com>, Muchun Song <songmuchun@bytedance.com>, Mike Kravetz <mike.kravetz@oracle.com>, Andrew Morton <akpm@linux-foundation.org> Subject: Re: [PATCH RFC 0/9] mm, sparse-vmemmap: Introduce compound pagemaps Date: Tue, 23 Feb 2021 17:15:04 +0000 [thread overview] Message-ID: <1cf0adb0-9692-bcb2-4d3d-374ba3164994@oracle.com> (raw) In-Reply-To: <CAPcyv4joomjhZYaCBNrYjvATSYgECfHYOZy=n_QVKqX7D_ReZQ@mail.gmail.com> On 2/23/21 4:44 PM, Dan Williams wrote: > On Tue, Feb 23, 2021 at 8:30 AM Joao Martins <joao.m.martins@oracle.com> wrote: >> >> On 2/20/21 1:18 AM, Dan Williams wrote: >>> On Tue, Dec 8, 2020 at 9:32 AM Joao Martins <joao.m.martins@oracle.com> wrote: >>>> Patch 6 - 8: Optimize grabbing/release a page refcount changes given that we >>>> are working with compound pages i.e. we do 1 increment/decrement to the head >>>> page for a given set of N subpages compared as opposed to N individual writes. >>>> {get,pin}_user_pages_fast() for zone_device with compound pagemap consequently >>>> improves considerably, and unpin_user_pages() improves as well when passed a >>>> set of consecutive pages: >>>> >>>> before after >>>> (get_user_pages_fast 1G;2M page size) ~75k us -> ~3.2k ; ~5.2k us >>>> (pin_user_pages_fast 1G;2M page size) ~125k us -> ~3.4k ; ~5.5k us >>> >>> Compelling! >>> >> >> BTW is there any reason why we don't support pin_user_pages_fast() with FOLL_LONGTERM for >> device-dax? >> > > Good catch. > > Must have been an oversight of the conversion. FOLL_LONGTERM collides > with filesystem operations, but not device-dax. hmmmm, fwiw, it was unilaterally disabled for any devmap pmd/pud in commit 7af75561e171 ("mm/gup: add FOLL_LONGTERM capability to GUP fast") and I must only assume that by "DAX pages" the submitter was only referring to fs-dax pages. > In fact that's the > motivation for device-dax in the first instance, no need to coordinate > runtime physical address layout changes because the device is > statically allocated. > /me nods >> Looking at the history, I understand that fsdax can't support it atm, but I am not sure >> that the same holds for device-dax. I have this small chunk (see below the scissors mark) >> which relaxes this for a pgmap of type MEMORY_DEVICE_GENERIC, albeit not sure if there is >> a fundamental issue for the other types that makes this an unwelcoming change. >> >> Joao >> >> --------------------->8--------------------- >> >> Subject: [PATCH] mm/gup: allow FOLL_LONGTERM pin-fast for >> MEMORY_DEVICE_GENERIC >> >> The downside would be one extra lookup in dev_pagemap tree >> for other pgmap->types (P2P, FSDAX, PRIVATE). But just one >> per gup-fast() call. > > I'd guess a dev_pagemap lookup is faster than a get_user_pages slow > path. It should be measurable that this change is at least as fast or > faster than falling back to the slow path, but it would be good to > measure. > But with the changes I am/will-be making I hope gup-fast and gup-slow will be as fast (for present pmd/puds ofc, as the fault makes it slower). I'll formally submit below patch, once I ran over the numbers. > Code changes look good to me. > Cool! Will add in the suggested change below. >> >> Signed-off-by: Joao Martins <joao.m.martins@oracle.com> >> --- >> include/linux/mm.h | 5 +++++ >> mm/gup.c | 24 +++++++++++++----------- >> 2 files changed, 18 insertions(+), 11 deletions(-) >> >> diff --git a/include/linux/mm.h b/include/linux/mm.h >> index 32f0c3986d4f..c89a049bbd7a 100644 >> --- a/include/linux/mm.h >> +++ b/include/linux/mm.h >> @@ -1171,6 +1171,11 @@ static inline bool is_pci_p2pdma_page(const struct page *page) >> page->pgmap->type == MEMORY_DEVICE_PCI_P2PDMA; >> } >> >> +static inline bool devmap_longterm_available(const struct dev_pagemap *pgmap) >> +{ > > I'd call this devmap_can_longterm(). > Ack.
next prev parent reply other threads:[~2021-02-23 17:15 UTC|newest] Thread overview: 147+ 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 ` Joao Martins 2020-12-08 17:28 ` [PATCH RFC 1/9] memremap: add ZONE_DEVICE support for compound pages Joao Martins 2020-12-08 17:28 ` Joao Martins 2020-12-09 5:59 ` John Hubbard 2020-12-09 5:59 ` John Hubbard 2020-12-09 6:33 ` Matthew Wilcox 2020-12-09 6:33 ` Matthew Wilcox 2020-12-09 13:12 ` Joao Martins 2020-12-09 13:12 ` Joao Martins 2021-02-20 1:43 ` Dan Williams 2021-02-20 1:43 ` Dan Williams 2021-02-22 11:24 ` Joao Martins 2021-02-22 11:24 ` Joao Martins 2021-02-22 20:37 ` Dan Williams 2021-02-22 20:37 ` Dan Williams 2021-02-23 15:46 ` Joao Martins 2021-02-23 15:46 ` Joao Martins 2021-02-23 16:50 ` Dan Williams 2021-02-23 16:50 ` Dan Williams 2021-02-23 17:18 ` Joao Martins 2021-02-23 17:18 ` Joao Martins 2021-02-23 18:18 ` Dan Williams 2021-02-23 18:18 ` Dan Williams 2021-03-10 18:12 ` Joao Martins 2021-03-10 18:12 ` Joao Martins 2021-03-12 5:54 ` Dan Williams 2021-03-12 5:54 ` Dan Williams 2021-02-20 1:24 ` Dan Williams 2021-02-20 1:24 ` Dan Williams 2021-02-22 11:09 ` Joao Martins 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 2020-12-08 17:28 ` Joao Martins 2020-12-09 6:16 ` John Hubbard 2020-12-09 6:16 ` John Hubbard 2020-12-09 13:51 ` Joao Martins 2020-12-09 13:51 ` Joao Martins 2021-02-20 1:49 ` Dan Williams 2021-02-20 1:49 ` Dan Williams 2021-02-22 11:26 ` Joao Martins 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 17:28 ` Joao Martins 2020-12-08 17:38 ` 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 2020-12-08 17:28 ` Joao Martins 2021-02-20 3:34 ` Dan Williams 2021-02-20 3:34 ` Dan Williams 2021-02-22 11:42 ` Joao Martins 2021-02-22 11:42 ` Joao Martins 2021-02-22 22:40 ` Dan Williams 2021-02-22 22:40 ` Dan Williams 2021-02-23 15:46 ` Joao Martins 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 2020-12-08 17:28 ` Joao Martins 2021-02-20 6:17 ` Dan Williams 2021-02-20 6:17 ` Dan Williams 2021-02-22 12:01 ` Joao Martins 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 ` Joao Martins 2020-12-08 17:28 ` [PATCH RFC 6/9] mm/gup: Grab head page refcount once for group of subpages Joao Martins 2020-12-08 17:28 ` Joao Martins 2020-12-08 19:49 ` Jason Gunthorpe 2020-12-09 11:05 ` Joao Martins 2020-12-09 11:05 ` Joao Martins 2020-12-09 15:15 ` Jason Gunthorpe 2020-12-09 16:02 ` Joao Martins 2020-12-09 16:02 ` Joao Martins 2020-12-09 16:24 ` Jason Gunthorpe 2020-12-09 17:27 ` Joao Martins 2020-12-09 17:27 ` Joao Martins 2020-12-09 18:14 ` Matthew Wilcox 2020-12-09 18:14 ` Matthew Wilcox 2020-12-09 19:08 ` Jason Gunthorpe 2020-12-10 15:43 ` Joao Martins 2020-12-10 15:43 ` Joao Martins 2020-12-09 4:40 ` John Hubbard 2020-12-09 4:40 ` John Hubbard 2020-12-09 13:44 ` Joao Martins 2020-12-09 13:44 ` Joao Martins 2020-12-08 17:28 ` [PATCH RFC 7/9] mm/gup: Decrement head page " Joao Martins 2020-12-08 17:28 ` Joao Martins 2020-12-08 19:34 ` Jason Gunthorpe 2020-12-09 5:06 ` John Hubbard 2020-12-09 5:06 ` John Hubbard 2020-12-09 13:43 ` Jason Gunthorpe 2020-12-09 12:17 ` Joao Martins 2020-12-09 12:17 ` Joao Martins 2020-12-17 19:05 ` Joao Martins 2020-12-17 19:05 ` Joao Martins 2020-12-17 20:05 ` Jason Gunthorpe 2020-12-17 22:34 ` Joao Martins 2020-12-17 22:34 ` Joao Martins 2020-12-18 14:25 ` Jason Gunthorpe 2020-12-19 2:06 ` John Hubbard 2020-12-19 2:06 ` John Hubbard 2020-12-19 13:10 ` Joao Martins 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 2020-12-08 17:29 ` Joao Martins 2020-12-08 19:29 ` Jason Gunthorpe 2020-12-09 10:59 ` Joao Martins 2020-12-09 10:59 ` Joao Martins 2020-12-19 13:15 ` Joao Martins 2020-12-19 13:15 ` Joao Martins 2020-12-09 5:18 ` John Hubbard 2020-12-09 5:18 ` John Hubbard 2020-12-08 17:29 ` [PATCH RFC 9/9] mm: Add follow_devmap_page() for devdax vmas Joao Martins 2020-12-08 17:29 ` Joao Martins 2020-12-08 19:57 ` Jason Gunthorpe 2020-12-09 8:05 ` Christoph Hellwig 2020-12-09 8:05 ` Christoph Hellwig 2020-12-09 11:19 ` Joao Martins 2020-12-09 11:19 ` Joao Martins 2020-12-09 5:23 ` John Hubbard 2020-12-09 5:23 ` John Hubbard 2020-12-09 9:38 ` [PATCH RFC 0/9] mm, sparse-vmemmap: Introduce compound pagemaps David Hildenbrand 2020-12-09 9:38 ` David Hildenbrand 2020-12-09 9:52 ` [External] " Muchun Song 2020-12-09 9:52 ` Muchun Song 2021-02-20 1:18 ` Dan Williams 2021-02-20 1:18 ` Dan Williams 2021-02-22 11:06 ` Joao Martins 2021-02-22 11:06 ` Joao Martins 2021-02-22 14:32 ` Joao Martins 2021-02-22 14:32 ` Joao Martins 2021-02-23 16:28 ` Joao Martins 2021-02-23 16:28 ` Joao Martins 2021-02-23 16:44 ` Dan Williams 2021-02-23 16:44 ` Dan Williams 2021-02-23 17:15 ` Joao Martins [this message] 2021-02-23 17:15 ` Joao Martins 2021-02-23 18:15 ` Dan Williams 2021-02-23 18:15 ` Dan Williams 2021-02-23 18:54 ` Jason Gunthorpe 2021-02-23 22:48 ` Dan Williams 2021-02-23 22:48 ` Dan Williams 2021-02-23 23:07 ` Jason Gunthorpe 2021-02-24 0:14 ` Dan Williams 2021-02-24 0:14 ` Dan Williams 2021-02-24 1:00 ` Jason Gunthorpe 2021-02-24 1:32 ` Dan Williams 2021-02-24 1:32 ` Dan Williams
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