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* [PATCH RFC v2 0/2] mm: add huge pfnmap support for remap_pfn_range()
@ 2025-10-16 11:27 Yin Tirui
  2025-10-16 11:27 ` [PATCH RFC 1/2] pgtable: add pte_clrhuge() implementation for arm64 and riscv Yin Tirui
                   ` (2 more replies)
  0 siblings, 3 replies; 7+ messages in thread
From: Yin Tirui @ 2025-10-16 11:27 UTC (permalink / raw)
  To: akpm, david, lorenzo.stoakes, Liam.Howlett, vbabka, rppt, surenb,
	mhocko, ziy, baolin.wang, npache, ryan.roberts, dev.jain, baohua,
	catalin.marinas, will, paul.walmsley, palmer, aou, alex,
	anshuman.khandual, yangyicong, ardb, willy, apopple,
	samuel.holland, luxu.kernel, abrestic, yongxuan.wang, linux-mm,
	linux-kernel, linux-arm-kernel, linux-riscv
  Cc: wangkefeng.wang, chenjun102, yintirui

v2:
- remove "nohugepfnmap" boot option and "pfnmap_max_page_shift" variable.
- zap_deposited_table for non-special pmd.
- move set_pmd_at() inside pmd_lock.
- prevent PMD mapping creation when pgtable allocation fails.
- defer the refactor of pte_clrhuge() to a separate patch series. For now,
  add a TODO to track this.

v1: https://lore.kernel.org/linux-mm/20250923133104.926672-1-yintirui@huawei.com/

Overview
========
This patch series adds huge page support for remap_pfn_range(),
automatically creating huge mappings when prerequisites are satisfied
(size, alignment, architecture support, etc.) and falling back to
normal page mappings otherwise.

This work builds on Peter Xu's previous efforts on huge pfnmap
support [0].

TODO
====
- Add PUD-level huge page support. Currently, only PMD-level huge
pages are supported.
- Consider the logic related to vmap_page_range and extract
reusable common code.
- Refactor pte_clrhuge() and related functions.

Tests Done
==========
- Cross-build tests.
- Performance tests with custom device driver implementing mmap()
  with remap_pfn_range():
    - lat_mem_rd benchmark modified to use mmap(device_fd) instead of
      malloc() shows around 40% improvement in memory access latency with
      huge page support compared to normal page mappings.

      numactl -C 0 lat_mem_rd -t 4096M (stride=64)
      Memory Size (MB)    Without Huge Mapping With Huge Mapping Improvement
      ----------------    -----------------    --------------    -----------
      64.00               148.858 ns           100.780 ns        32.3%
      128.00              164.745 ns           103.537 ns        37.2%
      256.00              169.907 ns           103.179 ns        39.3%
      512.00              171.285 ns           103.072 ns        39.8%
      1024.00             173.054 ns           103.055 ns        40.4%
      2048.00             172.820 ns           103.091 ns        40.3%
      4096.00             172.877 ns           103.115 ns        40.4%

    - Custom memory copy operations on mmap(device_fd) show around 18% performance 
      improvement with huge page support compared to normal page mappings.

      numactl -C 0 memcpy_test (memory copy performance test)
      Memory Size (MB)    Without Huge Mapping With Huge Mapping Improvement
      ----------------    -----------------    --------------    -----------
      1024.00             95.76 ms             77.91 ms          18.6%
      2048.00             190.87 ms            155.64 ms         18.5%
      4096.00             380.84 ms            311.45 ms         18.2%

[0] https://lore.kernel.org/all/20240826204353.2228736-2-peterx@redhat.com/T/#u

Yin Tirui (2):
  pgtable: add pte_clrhuge() implementation for arm64 and riscv
  mm: add PMD-level huge page support for remap_pfn_range()

 arch/arm64/include/asm/pgtable.h |  8 +++++++
 arch/riscv/include/asm/pgtable.h |  5 ++++
 include/linux/pgtable.h          |  6 ++++-
 mm/huge_memory.c                 | 26 +++++++++++++++------
 mm/memory.c                      | 40 ++++++++++++++++++++++++++++++++
 5 files changed, 77 insertions(+), 8 deletions(-)

-- 
2.43.0



^ permalink raw reply	[flat|nested] 7+ messages in thread
* [PATCH RFC 0/2] mm: add huge pfnmap support for remap_pfn_range()
@ 2025-09-23 13:31 Yin Tirui
  2025-09-23 13:31 ` [PATCH RFC 1/2] pgtable: add pte_clrhuge() implementation for arm64 and riscv Yin Tirui
  0 siblings, 1 reply; 7+ messages in thread
From: Yin Tirui @ 2025-09-23 13:31 UTC (permalink / raw)
  To: akpm, david, lorenzo.stoakes, Liam.Howlett, vbabka, rppt, surenb,
	mhocko, ziy, baolin.wang, npache, ryan.roberts, dev.jain, baohua,
	catalin.marinas, will, paul.walmsley, palmer, aou, alex,
	anshuman.khandual, yangyicong, ardb, willy, apopple,
	samuel.holland, luxu.kernel, abrestic, yongxuan.wang, linux-mm,
	linux-kernel, linux-arm-kernel, linux-riscv
  Cc: wangkefeng.wang, chenjun102, yintirui

Overview
========
This patch series adds huge page support for remap_pfn_range(),
automatically creating huge mappings when prerequisites are satisfied
(size, alignment, architecture support, etc.) and falling back to
normal page mappings otherwise.

This work builds on Peter Xu's previous efforts on huge pfnmap
support [0].

TODO
====
- Add PUD-level huge page support. Currently, only PMD-level huge
pages are supported.
- Consider the logic related to vmap_page_range and extract
reusable common code.

Tests Done
==========
- Cross-build tests.
- Performance tests with custom device driver implementing mmap()
  with remap_pfn_range():
    - lat_mem_rd benchmark modified to use mmap(device_fd) instead of
      malloc() shows around 40% improvement in memory access latency with
      huge page support compared to normal page mappings.

      numactl -C 0 lat_mem_rd -t 4096M (stride=64)
      Memory Size (MB)    Without Huge Mapping With Huge Mapping Improvement
      ----------------    -----------------    --------------    -----------
      64.00               148.858 ns           100.780 ns        32.3%
      128.00              164.745 ns           103.537 ns        37.2%
      256.00              169.907 ns           103.179 ns        39.3%
      512.00              171.285 ns           103.072 ns        39.8%
      1024.00             173.054 ns           103.055 ns        40.4%
      2048.00             172.820 ns           103.091 ns        40.3%
      4096.00             172.877 ns           103.115 ns        40.4%

    - Custom memory copy operations on mmap(device_fd) show around 18% performance 
      improvement with huge page support compared to normal page mappings.

      numactl -C 0 memcpy_test (memory copy performance test)
      Memory Size (MB)    Without Huge Mapping With Huge Mapping Improvement
      ----------------    -----------------    --------------    -----------
      1024.00             95.76 ms             77.91 ms          18.6%
      2048.00             190.87 ms            155.64 ms         18.5%
      4096.00             380.84 ms            311.45 ms         18.2%

[0] https://lore.kernel.org/all/20240826204353.2228736-2-peterx@redhat.com/T/#u

Yin Tirui (2):
  pgtable: add pte_clrhuge() implementation for arm64 and riscv
  mm: add PMD-level huge page support for remap_pfn_range()

 arch/arm64/include/asm/pgtable.h |  8 ++++
 arch/riscv/include/asm/pgtable.h |  5 +++
 include/linux/pgtable.h          |  6 ++-
 mm/huge_memory.c                 | 22 +++++++---
 mm/memory.c                      | 74 ++++++++++++++++++++++++++++----
 5 files changed, 98 insertions(+), 17 deletions(-)

-- 
2.43.0



^ permalink raw reply	[flat|nested] 7+ messages in thread
end of thread, other threads:[~2025-10-18  3:12 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2025-10-16 11:27 [PATCH RFC v2 0/2] mm: add huge pfnmap support for remap_pfn_range() Yin Tirui
2025-10-16 11:27 ` [PATCH RFC 1/2] pgtable: add pte_clrhuge() implementation for arm64 and riscv Yin Tirui
2025-10-16 18:22   ` Matthew Wilcox
2025-10-18  3:12     ` Yin Tirui
2025-10-16 11:27 ` [PATCH RFC 2/2] mm: add PMD-level huge page support for remap_pfn_range() Yin Tirui
2025-10-16 16:23 ` [syzbot ci] Re: mm: add huge pfnmap " syzbot ci
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2025-09-23 13:31 [PATCH RFC 0/2] " Yin Tirui
2025-09-23 13:31 ` [PATCH RFC 1/2] pgtable: add pte_clrhuge() implementation for arm64 and riscv Yin Tirui

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