[PATCH v4 0/8] Avoid cache trashing on clearing huge/gigantic page

[Kirill A. Shutemov]

From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>

Clearing a 2MB huge page will typically blow away several levels of CPU
caches.  To avoid this only cache clear the 4K area around the fault
address and use a cache avoiding clears for the rest of the 2MB area.

This patchset implements cache avoiding version of clear_page only for
x86. If an architecture wants to provide cache avoiding version of
clear_page it should to define ARCH_HAS_USER_NOCACHE to 1 and implement
clear_page_nocache() and clear_user_highpage_nocache().

v4:
  - vm.clear_huge_page_nocache sysctl;
  - rework page iteration in clear_{huge,gigantic}_page according to
    Andrea Arcangeli suggestion;
v3:
  - Rebased to current Linus' tree. kmap_atomic() build issue is fixed;
  - Pass fault address to clear_huge_page(). v2 had problem with clearing
    for sizes other than HPAGE_SIZE;
  - x86: fix 32bit variant. Fallback version of clear_page_nocache() has
    been added for non-SSE2 systems;
  - x86: clear_page_nocache() moved to clear_page_{32,64}.S;
  - x86: use pushq_cfi/popq_cfi instead of push/pop;
v2:
  - No code change. Only commit messages are updated;
  - RFC mark is dropped;

Andi Kleen (5):
  THP: Use real address for NUMA policy
  THP: Pass fault address to __do_huge_pmd_anonymous_page()
  x86: Add clear_page_nocache
  mm: make clear_huge_page cache clear only around the fault address
  x86: switch the 64bit uncached page clear to SSE/AVX v2

Kirill A. Shutemov (3):
  hugetlb: pass fault address to hugetlb_no_page()
  mm: pass fault address to clear_huge_page()
  mm: implement vm.clear_huge_page_nocache sysctl

 Documentation/sysctl/vm.txt      |   13 ++++++
 arch/x86/include/asm/page.h      |    2 +
 arch/x86/include/asm/string_32.h |    5 ++
 arch/x86/include/asm/string_64.h |    5 ++
 arch/x86/lib/Makefile            |    3 +-
 arch/x86/lib/clear_page_32.S     |   72 +++++++++++++++++++++++++++++++++++
 arch/x86/lib/clear_page_64.S     |   78 ++++++++++++++++++++++++++++++++++++++
 arch/x86/mm/fault.c              |    7 +++
 include/linux/mm.h               |    7 +++-
 kernel/sysctl.c                  |   12 ++++++
 mm/huge_memory.c                 |   17 ++++----
 mm/hugetlb.c                     |   39 ++++++++++---------
 mm/memory.c                      |   72 ++++++++++++++++++++++++++++++----
 13 files changed, 294 insertions(+), 38 deletions(-)
 create mode 100644 arch/x86/lib/clear_page_32.S

-- 
1.7.7.6

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