Hi,
I revised the split page table lock patch (v1 is [1]), and got some numbers
to confirm the performance improvement.
This patchset simply replaces all of locking/unlocking of mm->page_table_lock
in hugepage context with page->ptl when USE_SPLIT_PTLOCKS is true, which
breaks single mm wide locking into multiple small (pmd/pte sized) address
range locking, so we can clearly expect better performance when many threads
access to virtual memory of a process simultaneously.
Here is the result of my testing [2], where I measured the time (in seconds)
taken to execute a specific workload in various conditions. So the smaller
number means the better performance. The workload is like this:
1) allocate N hugepages/thps and touch them once,
2) create T threads with pthread_create(), and
3) each thread accesses to the whole pages sequentially 10 times.
| hugetlb | thp |
N T | v3.11-rc3 | patched | v3.11-rc3 | patched |
100 100 | 0.13 (+-0.04) | 0.07 (+-0.01) | 0.10 (+-0.01) | 0.08 (+-0.03) |
100 3000 | 11.67 (+-0.47) | 6.54 (+-0.38) | 11.21 (+-0.28) | 6.44 (+-0.26) |
6000 100 | 2.87 (+-0.07) | 2.79 (+-0.06) | 3.21 (+-0.06) | 3.10 (+-0.06) |
6000 3000 | 18.76 (+-0.50) | 13.68 (+-0.35) | 19.44 (+-0.78) | 14.03 (+-0.43) |
* Numbers are the averages (and stddev) of 20 testing respectively.
This result shows that for both of hugetlb/thp patched kernel provides better
results, so patches works fine. The performance gain is larger for larger T.
Interestingly, in more detailed analysis the improvement mostly comes from 2).
I got a little improvement for 3), but no visible improvement for 1).
[1] http://thread.gmane.org/gmane.linux.kernel.mm/100856/focus=100858
[2] https://github.com/Naoya-Horiguchi/test_split_page_table_lock_for_hugepage
Naoya Horiguchi (2):
hugetlbfs: support split page table lock
thp: support split page table lock
arch/powerpc/mm/hugetlbpage.c | 6 +-
arch/powerpc/mm/pgtable_64.c | 8 +-
arch/s390/mm/pgtable.c | 4 +-
arch/sparc/mm/tlb.c | 4 +-
arch/tile/mm/hugetlbpage.c | 6 +-
fs/proc/task_mmu.c | 17 +++--
include/linux/huge_mm.h | 11 +--
include/linux/hugetlb.h | 20 +++++
include/linux/mm.h | 3 +
mm/huge_memory.c | 170 +++++++++++++++++++++++++-----------------
mm/hugetlb.c | 92 ++++++++++++++---------
mm/memcontrol.c | 14 ++--
mm/memory.c | 15 ++--
mm/mempolicy.c | 5 +-
mm/migrate.c | 12 +--
mm/mprotect.c | 5 +-
mm/pgtable-generic.c | 10 +--
mm/rmap.c | 13 ++--
18 files changed, 251 insertions(+), 164 deletions(-)
Thanks,
Naoya Horiguchi
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>