Subject: [PATCH V1 00/11] powerpc/mm/book3s64: Support for split pmd ptlock

From: "Aneesh Kumar K.V" <[email-masked]>
Date: Mon, 16 Apr 2018 16:57:12 +0530

This patch series add split pmd pagetable lock for book3s64. nohash64 also should
be able to switch to this. I need to workout the code dependency. This series
also migh have broken the build on platforms otherthan book3s64. I am sending this early
to get feedback on whether we should continue with the approach.

We switch the pmd allocator to use something similar to what we already use for
level 4 pagetable allocation. We get an order 0 page and divide that to fragments
and hand over fragments when we get request for a pmd pagetable. The pmd lock is
now stashed in the struct page backing the allocated page.

The series helps in reducing lock contention on mm->page_table_lock.

without patch

    32.72%  mmap_bench  [kernel.vmlinux]            [k] do_raw_spin_lock
            |
            ---do_raw_spin_lock
               |
                --32.68%--0
                          |
                          |--15.82%--pte_fragment_alloc
                          |          |
                          |           --15.79%--do_huge_pmd_anonymous_page
                          |                     __handle_mm_fault
                          |                     handle_mm_fault
                          |                     __do_page_fault
                          |                     handle_page_fault
                          |                     test_mmap
                          |                     test_mmap
                          |                     start_thread
                          |                     __clone
                          |
                          |--14.95%--do_huge_pmd_anonymous_page
                          |          __handle_mm_fault
                          |          handle_mm_fault
                          |          __do_page_fault
                          |          handle_page_fault
                          |          test_mmap
                          |          test_mmap
                          |          start_thread
                          |          __clone
                          |

with patch

    12.89%  mmap_bench  [kernel.vmlinux]            [k] do_raw_spin_lock
            |
            ---do_raw_spin_lock
               |
                --12.83%--0
                          |
                          |--3.21%--pagevec_lru_move_fn
                          |          __lru_cache_add
                          |          |
                          |           --2.74%--do_huge_pmd_anonymous_page
                          |                     __handle_mm_fault
                          |                     handle_mm_fault
                          |                     __do_page_fault
                          |                     handle_page_fault
                          |                     test_mmap
                          |                     test_mmap
                          |                     start_thread
                          |                     __clone
                          |
                          |--3.11%--do_huge_pmd_anonymous_page
                          |          __handle_mm_fault
                          |          handle_mm_fault
                          |          __do_page_fault
                          |          handle_page_fault
                          |          test_mmap
                          |          test_mmap
                          |          start_thread
                          |          __clone

.....
                          |
                           --0.55%--pte_fragment_alloc
                                     |
                                      --0.55%--do_huge_pmd_anonymous_page
                                                __handle_mm_fault
                                                handle_mm_fault
                                                __do_page_fault
                                                handle_page_fault
                                                test_mmap
                                                test_mmap
                                                start_thread
                                                __clone

Aneesh Kumar K.V (11):
  powerpc/mm/book3s64: Move book3s64 code to pgtable-book3s64
  powerpc/kvm: Switch kvm pmd allocator to custom allocator
  powerpc/mm: Use pmd_lockptr instead of opencoding it
  powerpc/mm: Rename pte fragment functions
  powerpc/mm/book3e/64: Remove unsupported 64Kpage size from 64bit booke
  powerpc/mm/nohash: Remove pte fragment dependency from nohash
  powerpc/mm/book3s64/4k: Switch 4k pagesize config to use pagetable
    fragment
  powerpc/book3s64/mm: Simplify the rcu callback for page table free
  powerpc/mm: Implement helpers for pagetable fragment support at PMD
    level
  powerpc/mm: Use page fragments for allocation page table at PMD level
  powerpc/book3s64: Enable split pmd ptlock.

 arch/powerpc/include/asm/book3s/64/hash-4k.h     |   8 +-
 arch/powerpc/include/asm/book3s/64/hash-64k.h    |   7 +
 arch/powerpc/include/asm/book3s/64/hash.h        |  10 -
 arch/powerpc/include/asm/book3s/64/mmu.h         |   7 +-
 arch/powerpc/include/asm/book3s/64/pgalloc.h     |  46 +---
 arch/powerpc/include/asm/book3s/64/pgtable.h     |  20 +-
 arch/powerpc/include/asm/book3s/64/radix-4k.h    |   3 +
 arch/powerpc/include/asm/book3s/64/radix-64k.h   |   4 +
 arch/powerpc/include/asm/mmu-book3e.h            |   6 -
 arch/powerpc/include/asm/nohash/64/pgalloc.h     |  95 +++-----
 arch/powerpc/include/asm/nohash/64/pgtable-64k.h |  57 -----
 arch/powerpc/include/asm/nohash/64/pgtable.h     |   8 +-
 arch/powerpc/kvm/book3s_64_mmu_radix.c           |  36 ++-
 arch/powerpc/mm/hash_utils_64.c                  |   3 +-
 arch/powerpc/mm/mmu_context_book3s64.c           |  39 +++-
 arch/powerpc/mm/pgtable-book3s64.c               | 267 ++++++++++++++++++++++-
 arch/powerpc/mm/pgtable-hash64.c                 |   8 +-
 arch/powerpc/mm/pgtable-radix.c                  |   5 +-
 arch/powerpc/mm/pgtable_64.c                     | 171 ---------------
 arch/powerpc/platforms/Kconfig.cputype           |   4 +
 20 files changed, 427 insertions(+), 377 deletions(-)
 delete mode 100644 arch/powerpc/include/asm/nohash/64/pgtable-64k.h

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2.14.3