[RFC PATCH 0/9] powerpc: mm: Numa faults support for ppc64

[Aneesh Kumar K.V]

Hi,

This patch series add support for numa faults on ppc64 architecture. We steal the
_PAGE_COHERENCE bit and use that for indicating _PAGE_NUMA. We clear the _PAGE_PRESENT bit
and also invalidate the hpte entry on setting _PAGE_NUMA. The next fault on that
page will be considered a numa fault.


NOTE:
______
Issue:
I am finding large lock contention on page_table_lock with this series on a 95 cpu 4 node box with autonuma benchmark

I will out on vacation till NOV 6 without email access. Hence i will not be able to respond to review feedbacks
till then. 


lock_stat version 0.3
-------------------------------------------------------------------------------------------------------------------------------------------------------
                      class name    con-bounces    contentions   waittime-min   waittime-max waittime-total    acq-bounces   acquisitions   holdtime-mi  hold time hold total
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------

  &(&mm->page_table_lock)->rlock:     713531791      719610919           0.09     3038193.19 357867523236.3      729709189      750040162    0.0  236991.36  1159646899.68
  ------------------------------
  &(&mm->page_table_lock)->rlock              1          [<c000000000218880>] .anon_vma_prepare+0xb0/0x1e0
  &(&mm->page_table_lock)->rlock             93          [<c000000000207ebc>] .do_numa_page+0x4c/0x190
  &(&mm->page_table_lock)->rlock         301678          [<c0000000002139d4>] .change_protection+0x1d4/0x560
  &(&mm->page_table_lock)->rlock         244524          [<c000000000213be8>] .change_protection+0x3e8/0x560
  ------------------------------
  &(&mm->page_table_lock)->rlock              1          [<c000000000206a38>] .__do_fault+0x198/0x6b0
  &(&mm->page_table_lock)->rlock         704163          [<c0000000002139d4>] .change_protection+0x1d4/0x560
  &(&mm->page_table_lock)->rlock         207227          [<c000000000213be8>] .change_protection+0x3e8/0x560
  &(&mm->page_table_lock)->rlock             95          [<c000000000207ebc>] .do_numa_page+0x4c/0x190
 
-aneesh