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 16:28:57 +0000 [thread overview]
Message-ID: <6a18179e-65f7-367d-89a9-d5162f10fef0@oracle.com> (raw)
In-Reply-To: <CAPcyv4gQQ03-nhBNwLK6KDc953SVD1rOs7HFBo_Mu9LFTkXRgw@mail.gmail.com>
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?
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.
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)
+{
+ return pgmap->type == MEMORY_DEVICE_GENERIC;
+}
+
/* 127: arbitrary random number, small enough to assemble well */
#define page_ref_zero_or_close_to_overflow(page) \
((unsigned int) page_ref_count(page) + 127u <= 127u)
diff --git a/mm/gup.c b/mm/gup.c
index 222d1fdc5cfa..03e370d360e6 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2092,14 +2092,18 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned
long end,
goto pte_unmap;
if (pte_devmap(pte)) {
- if (unlikely(flags & FOLL_LONGTERM))
- goto pte_unmap;
-
pgmap = get_dev_pagemap(pte_pfn(pte), pgmap);
if (unlikely(!pgmap)) {
undo_dev_pagemap(nr, nr_start, flags, pages);
goto pte_unmap;
}
+
+ if (unlikely(flags & FOLL_LONGTERM) &&
+ !devmap_longterm_available(pgmap)) {
+ undo_dev_pagemap(nr, nr_start, flags, pages);
+ goto pte_unmap;
+ }
+
} else if (pte_special(pte))
goto pte_unmap;
@@ -2195,6 +2199,10 @@ static int __gup_device_huge(unsigned long pfn, unsigned long addr,
return 0;
}
+ if (unlikely(flags & FOLL_LONGTERM) &&
+ !devmap_longterm_available(pgmap))
+ return 0;
+
@@ -2356,12 +2364,9 @@ static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
if (!pmd_access_permitted(orig, flags & FOLL_WRITE))
return 0;
- if (pmd_devmap(orig)) {
- if (unlikely(flags & FOLL_LONGTERM))
- return 0;
+ if (pmd_devmap(orig))
return __gup_device_huge_pmd(orig, pmdp, addr, end, flags,
pages, nr);
- }
page = pmd_page(orig) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
refs = record_subpages(page, addr, end, pages + *nr);
@@ -2390,12 +2395,9 @@ static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr,
if (!pud_access_permitted(orig, flags & FOLL_WRITE))
return 0;
- if (pud_devmap(orig)) {
- if (unlikely(flags & FOLL_LONGTERM))
- return 0;
+ if (pud_devmap(orig))
return __gup_device_huge_pud(orig, pudp, addr, end, flags,
pages, nr);
- }
page = pud_page(orig) + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
refs = record_subpages(page, addr, end, pages + *nr);
--
2.17.1
_______________________________________________
Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org
To unsubscribe send an email to linux-nvdimm-leave@lists.01.org
next prev parent reply other threads:[~2021-02-23 16:29 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
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 [this message]
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=6a18179e-65f7-367d-89a9-d5162f10fef0@oracle.com \
--to=joao.m.martins@oracle.com \
--cc=akpm@linux-foundation.org \
--cc=dan.j.williams@intel.com \
--cc=jgg@ziepe.ca \
--cc=linux-mm@kvack.org \
--cc=linux-nvdimm@lists.01.org \
--cc=mike.kravetz@oracle.com \
--cc=songmuchun@bytedance.com \
--cc=willy@infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).