Hi Chen,

I love your patch! Yet something to improve:

[auto build test ERROR on tip/sched/core]
[also build test ERROR on tip/auto-latest linus/master v5.7-rc2 next-20200421]
[cannot apply to linux/master]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/Chen-Yu/sched-Clean-up-newidle_balance-and-pick_next_task/20200421-161412
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git 8f3d9f354286745c751374f5f1fcafee6b3f3136
config: nds32-defconfig (attached as .config)
compiler: nds32le-linux-gcc (GCC) 9.3.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day GCC_VERSION=9.3.0 make.cross ARCH=nds32 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kbuild test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   nds32le-linux-ld: kernel/sched/fair.o: in function `pick_next_task_fair':
   fair.c:(.text+0x1384): undefined reference to `newidle_balance'
>> nds32le-linux-ld: fair.c:(.text+0x1388): undefined reference to `newidle_balance'

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org