sched/numa: Evaluate move once per node

sched/numa: Evaluate move once per node

task_numa_compare() helps choose the best CPU to move or swap the
selected task. To achieve this task_numa_compare() is called for every
CPU in the node. Currently it evaluates if the task can be moved/swapped
for each of the CPUs. However the move evaluation is mostly independent
of the CPU. Evaluating the move logic once per node, provides scope for
simplifying task_numa_compare().

Running SPECjbb2005 on a 4 node machine and comparing bops/JVM
JVMS  LAST_PATCH  WITH_PATCH  %CHANGE
16    25705.2     25058.2     -2.51
1     74433       72950       -1.99

Running SPECjbb2005 on a 16 node machine and comparing bops/JVM
JVMS  LAST_PATCH  WITH_PATCH  %CHANGE
8     96589.6     105930      9.670
1     181830      178624      -1.76

(numbers from v1 based on v4.17-rc5)
Testcase       Time:         Min         Max         Avg      StdDev
numa01.sh      Real:      440.65      941.32      758.98      189.17
numa01.sh       Sys:      183.48      320.07      258.42       50.09
numa01.sh      User:    37384.65    71818.14    60302.51    13798.96
numa02.sh      Real:       61.24       65.35       62.49        1.49
numa02.sh       Sys:       16.83       24.18       21.40        2.60
numa02.sh      User:     5219.59     5356.34     5264.03       49.07
numa03.sh      Real:      822.04      912.40      873.55       37.35
numa03.sh       Sys:      118.80      140.94      132.90        7.60
numa03.sh      User:    62485.19    70025.01    67208.33     2967.10
numa04.sh      Real:      690.66      872.12      778.49       65.44
numa04.sh       Sys:      459.26      563.03      494.03       42.39
numa04.sh      User:    51116.44    70527.20    58849.44     8461.28
numa05.sh      Real:      418.37      562.28      525.77       54.27
numa05.sh       Sys:      299.45      481.00      392.49       64.27
numa05.sh      User:    34115.09    41324.02    39105.30     2627.68

Testcase       Time:         Min         Max         Avg      StdDev 	 %Change
numa01.sh      Real:      516.14      892.41      739.84      151.32 	 2.587%
numa01.sh       Sys:      153.16      192.99      177.70       14.58 	 45.42%
numa01.sh      User:    39821.04    69528.92    57193.87    10989.48 	 5.435%
numa02.sh      Real:       60.91       62.35       61.58        0.63 	 1.477%
numa02.sh       Sys:       16.47       26.16       21.20        3.85 	 0.943%
numa02.sh      User:     5227.58     5309.61     5265.17       31.04 	 -0.02%
numa03.sh      Real:      739.07      917.73      795.75       64.45 	 9.776%
numa03.sh       Sys:       94.46      136.08      109.48       14.58 	 21.39%
numa03.sh      User:    57478.56    72014.09    61764.48     5343.69 	 8.813%
numa04.sh      Real:      442.61      715.43      530.31       96.12 	 46.79%
numa04.sh       Sys:      224.90      348.63      285.61       48.83 	 72.97%
numa04.sh      User:    35836.84    47522.47    40235.41     3985.26 	 46.26%
numa05.sh      Real:      386.13      489.17      434.94       43.59 	 20.88%
numa05.sh       Sys:      144.29      438.56      278.80      105.78 	 40.77%
numa05.sh      User:    33255.86    36890.82    34879.31     1641.98 	 12.11%

Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1529514181-9842-3-git-send-email-srikar@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>