[PATCH 0/3] mm: split the file's i_mmap tree for NUMA

[Huang Shijie <huangsj@hygon.cn>]

  In NUMA, there are maybe many NUMA nodes and many CPUs.
For example, a Hygon's server has 12 NUMA nodes, and 384 CPUs.
In the UnixBench tests, there is a test "execl" which tests
the execve system call.

  When we test our server with "./Run -c 384 execl",
the test result is not good enough. The i_mmap locks contended heavily on
"libc.so" and "ld.so". For example, the i_mmap tree for "libc.so" can have 
over 6000 VMAs, all the VMAs can be in different NUMA mode.
The insert/remove operations do not run quickly enough.

patch 1 & patch 2 are try to hide the direct access of i_mmap.
patch 3 splits the i_mmap into sibling trees, and we can get better 
performance with this patch set:
    we can get 77% performance improvement(10 times average)


Huang Shijie (3):
  mm: use mapping_mapped to simplify the code
  mm: use get_i_mmap_root to access the file's i_mmap
  mm: split the file's i_mmap tree for NUMA

 arch/arm/mm/fault-armv.c   |  3 ++-
 arch/arm/mm/flush.c        |  3 ++-
 arch/nios2/mm/cacheflush.c |  3 ++-
 arch/parisc/kernel/cache.c |  4 ++-
 fs/dax.c                   |  3 ++-
 fs/hugetlbfs/inode.c       | 10 +++----
 fs/inode.c                 | 55 +++++++++++++++++++++++++++++++++++++-
 include/linux/fs.h         | 40 +++++++++++++++++++++++++++
 include/linux/mm.h         | 33 +++++++++++++++++++++++
 include/linux/mm_types.h   |  1 +
 kernel/events/uprobes.c    |  3 ++-
 mm/hugetlb.c               |  7 +++--
 mm/khugepaged.c            |  6 +++--
 mm/memory-failure.c        |  8 +++---
 mm/memory.c                |  8 +++---
 mm/mmap.c                  |  3 ++-
 mm/nommu.c                 | 11 +++++---
 mm/pagewalk.c              |  2 +-
 mm/rmap.c                  |  2 +-
 mm/vma.c                   | 36 +++++++++++++++++++------
 mm/vma_init.c              |  1 +
 21 files changed, 204 insertions(+), 38 deletions(-)

-- 
2.43.0