[PATHC v3 -next 0/3] Some optimizations about freezer

[Chen Ridong <chenridong@huawei.com>]

I optimized the freezer to reduce redundant loops, and I add helper
to make code concise.

The following subtree was tested to prove whether my optimizations are
effective.
   0
 / | \ \
A  B C  1
      / | \ \
     A  B C  2
        .....
	         n
               / | \
              A  B C

I tested by following steps:
1. freeze 0
2. unfreeze 0
3. freeze 0
4. freeze 1

And I measured the elapsed time(ns).

n=10
	freeze 0	unfreeze 0	freeze 0	freeze 1
BEFORE	106179390	94016050	110423650	95063770
AFTER	96473608	91054188	94936398	93198510

n=50
	freeze 0	unfreeze 0	freeze 0	freeze 1
BEFORE	109506660	105643800	105970220	96948940
AFTER	105244651	97357482	97517358	88466266

n=100
	freeze 0	unfreeze 0	freeze 0	freeze 1
BEFORE	127944210	122049330	120988900	101232850
AFTER	117298106	107034146	105696895	91977833

As shown above, after optimizations, it can save elapsed time.
By freezing 0 and subsequently freezing 1, the elapsed time is consistent,
indicating that my optimizations are highly effective.

---
v3:
- fix build warnings reported-by kernel test robot.

v2:
- open code inside the loop of cgroup_freeze instead of inline function.
- add helper to make code concise.
- remove selftest script(There are hierarchy test in test_freeze.c, I
  think that is enough for this series).

Chen Ridong (3):
  cgroup/freezer: Reduce redundant traversal for cgroup_freeze
  cgroup/freezer: Add cgroup CGRP_FROZEN flag update helper
  cgroup/freezer: Reduce redundant propagation for
    cgroup_propagate_frozen

 include/linux/cgroup-defs.h |   6 +-
 kernel/cgroup/freezer.c     | 110 ++++++++++++++++++------------------
 2 files changed, 59 insertions(+), 57 deletions(-)

-- 
2.34.1