[PATCH RFC 0/3] optimize kswapd when it does reclaim for hugepage

[Jia He <hejianet@gmail.com>]

If there is a server with uneven numa memory layout:
available: 7 nodes (0-6)
node 0 cpus: 0 1 2 3 4 5 6 7
node 0 size: 6603 MB
node 0 free: 91 MB
node 1 cpus:
node 1 size: 12527 MB
node 1 free: 157 MB
node 2 cpus:
node 2 size: 15087 MB
node 2 free: 189 MB
node 3 cpus:
node 3 size: 16111 MB
node 3 free: 205 MB
node 4 cpus: 8 9 10 11 12 13 14 15
node 4 size: 24815 MB
node 4 free: 310 MB
node 5 cpus:
node 5 size: 4095 MB
node 5 free: 61 MB
node 6 cpus:
node 6 size: 22750 MB
node 6 free: 283 MB
node distances:
node   0   1   2   3   4   5   6
  0:  10  20  40  40  40  40  40
  1:  20  10  40  40  40  40  40
  2:  40  40  10  20  40  40  40
  3:  40  40  20  10  40  40  40
  4:  40  40  40  40  10  20  40
  5:  40  40  40  40  20  10  40
  6:  40  40  40  40  40  40  10

In this case node 5 has less memory and we will alloc the hugepages
from these nodes one by one after we trigger 
echo 4000 > /proc/sys/vm/nr_hugepages

Then the kswapd5 will take 100% cpu for a long time. This is a livelock
issue in kswapd. This patch set fixes it.

The 3rd patch improves the kswapd's bad performance significantly.

Jia He (3):
  mm/hugetlb: split alloc_fresh_huge_page_node into fast and slow path
  mm, vmscan: limit kswapd loop if no progress is made
  mm, vmscan: correct prepare_kswapd_sleep return value

 mm/hugetlb.c |  9 +++++++++
 mm/vmscan.c  | 28 ++++++++++++++++++++++++----
 2 files changed, 33 insertions(+), 4 deletions(-)

-- 
2.5.5

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