[RFC PATCH 0/2] Prioritize idle cpus over SCHED_IDLE ones

Abel Wu posted 2 patches 11 months ago
kernel/sched/fair.c | 40 ++++++++++++++++++++++++----------------
1 file changed, 24 insertions(+), 16 deletions(-)
[RFC PATCH 0/2] Prioritize idle cpus over SCHED_IDLE ones
Posted by Abel Wu 11 months ago
Since commit

  17346452b25b ("sched/fair: Make sched-idle CPU selection consistent")

the SCHED_IDLE cpus are given equal or more preference over idle ones in
fast- and slow-path of select_task_rq_fair(). This works well in flattened
cgroup hierarchy, e.g. all tasks running inside root cgroup, but may not
ideal in a deeper hierarchy where SCHED_IDLE doesn't mean anything between
entities whose parents are different. Hence a SCHED_IDLE cpu does NOT
necessarily implies any of the following:

 - It is a less loaded cpu (since the parent of its topmost idle
   ancestor could be a 'giant' entity with large cpu.weight).

 - It can be expected to be preempted by a newly woken task soon
   enough (which actually depends on their ancestors who have
   common parent).

As a less loaded cpu probably has better ability to serve the newly
woken task, which also applies to the SCHED_IDLE cpus that less loaded
SCHED_IDLE cpu might be easier and faster preempted, let's not special
case SCHED_IDLE cpus at least in slowpath when selecting.

  [ Plan to try the same in SIS, that is selecting a less loaded cpu
    and get rid of ambiguous sched_idle_cpu(). Comments and suggests
    are really appreciated. ]

Some benchmarks are tested in a Intel(R) Xeon(R) CPU E5-2650 v4 machine
based on tip/master ec3106906cbf, and are tested in following two setup:

		(t1)			(t2)
		root			root
		/  \\			/  \
	benchmark   noise	benchmark   X
					     \\
					     noise

where noise comes from a SCHED_IDLE cgroup. I didn't see an obvious diff
in hackbench or tbench, but not schbench.

				vanilla-t1	       patched-t1
Lat 50.0th-qrtle-1         8.00 (   0.00%)        8.00 (   0.00%)
Lat 90.0th-qrtle-1        13.00 (   0.00%)       13.00 (   0.00%)
Lat 99.0th-qrtle-1        19.00 (   0.00%)       18.00 (   5.26%)
Lat 99.9th-qrtle-1        22.00 (   0.00%)       22.00 (   0.00%)
Lat 20.0th-qrtle-1       257.00 (   0.00%)      259.00 (  -0.78%)
Lat 50.0th-qrtle-2         8.00 (   0.00%)        9.00 ( -12.50%)
Lat 90.0th-qrtle-2        13.00 (   0.00%)       13.00 (   0.00%)
Lat 99.0th-qrtle-2        19.00 (   0.00%)       19.00 (   0.00%)
Lat 99.9th-qrtle-2        23.00 (   0.00%)       24.00 (  -4.35%)
Lat 20.0th-qrtle-2       484.00 (   0.00%)      434.00 (  10.33%)
Lat 50.0th-qrtle-4         9.00 (   0.00%)        9.00 (   0.00%)
Lat 90.0th-qrtle-4        14.00 (   0.00%)       14.00 (   0.00%)
Lat 99.0th-qrtle-4        19.00 (   0.00%)       19.00 (   0.00%)
Lat 99.9th-qrtle-4        25.00 (   0.00%)       24.00 (   4.00%)
Lat 20.0th-qrtle-4       877.00 (   0.00%)      857.00 (   2.28%)
Lat 50.0th-qrtle-8         9.00 (   0.00%)        9.00 (   0.00%)
Lat 90.0th-qrtle-8        14.00 (   0.00%)       15.00 (  -7.14%)
Lat 99.0th-qrtle-8        20.00 (   0.00%)       21.00 (  -5.00%)
Lat 99.9th-qrtle-8        26.00 (   0.00%)       26.00 (   0.00%)
Lat 20.0th-qrtle-8      1698.00 (   0.00%)     1598.00 (   5.89%)
Lat 50.0th-qrtle-16       10.00 (   0.00%)       10.00 (   0.00%)
Lat 90.0th-qrtle-16       15.00 (   0.00%)       15.00 (   0.00%)
Lat 99.0th-qrtle-16       20.00 (   0.00%)       20.00 (   0.00%)
Lat 99.9th-qrtle-16       28.00 (   0.00%)       27.00 (   3.57%)
Lat 20.0th-qrtle-16     2900.00 (   0.00%)     2860.00 (   1.38%)
Lat 50.0th-qrtle-23        9.00 (   0.00%)        9.00 (   0.00%)
Lat 90.0th-qrtle-23       15.00 (   0.00%)       15.00 (   0.00%)
Lat 99.0th-qrtle-23       49.00 (   0.00%)       28.00 (  42.86%)
Lat 99.9th-qrtle-23     1602.00 (   0.00%)     1458.00 (   8.99%)
Lat 20.0th-qrtle-23     3796.00 (   0.00%)     3804.00 (  -0.21%)

				vanilla-t2	       patched-t2
Lat 50.0th-qrtle-1        10.00 (   0.00%)        9.00 (  10.00%)
Lat 90.0th-qrtle-1       271.00 (   0.00%)      272.00 (  -0.37%)
Lat 99.0th-qrtle-1      1013.00 (   0.00%)      793.00 (  21.72%)
Lat 99.9th-qrtle-1      1998.00 (   0.00%)     1642.00 (  17.82%)
Lat 20.0th-qrtle-1       262.00 (   0.00%)      262.00 (   0.00%)
Lat 50.0th-qrtle-2        10.00 (   0.00%)        9.00 (  10.00%)
Lat 90.0th-qrtle-2       531.00 (   0.00%)      510.00 (   3.95%)
Lat 99.0th-qrtle-2      1034.00 (   0.00%)      933.00 (   9.77%)
Lat 99.9th-qrtle-2      1846.00 (   0.00%)     1614.00 (  12.57%)
Lat 20.0th-qrtle-2       517.00 (   0.00%)      517.00 (   0.00%)
Lat 50.0th-qrtle-4        10.00 (   0.00%)       10.00 (   0.00%)
Lat 90.0th-qrtle-4       523.00 (   0.00%)      494.00 (   5.54%)
Lat 99.0th-qrtle-4       973.00 (   0.00%)      901.00 (   7.40%)
Lat 99.9th-qrtle-4      1618.00 (   0.00%)     1606.00 (   0.74%)
Lat 20.0th-qrtle-4      1015.00 (   0.00%)     1001.00 (   1.38%)
Lat 50.0th-qrtle-8        11.00 (   0.00%)       10.00 (   9.09%)
Lat 90.0th-qrtle-8       527.00 (   0.00%)      454.00 (  13.85%)
Lat 99.0th-qrtle-8       931.00 (   0.00%)      901.00 (   3.22%)
Lat 99.9th-qrtle-8      1598.00 (   0.00%)     1582.00 (   1.00%)
Lat 20.0th-qrtle-8      1738.00 (   0.00%)     1666.00 (   4.14%)
Lat 50.0th-qrtle-16        9.00 (   0.00%)        9.00 (   0.00%)
Lat 90.0th-qrtle-16      410.00 (   0.00%)      243.00 (  40.73%)
Lat 99.0th-qrtle-16      979.00 (   0.00%)      891.00 (   8.99%)
Lat 99.9th-qrtle-16     1486.00 (   0.00%)     1470.00 (   1.08%)
Lat 20.0th-qrtle-16     2708.00 (   0.00%)     2708.00 (   0.00%)
Lat 50.0th-qrtle-23        8.00 (   0.00%)        9.00 ( -12.50%)
Lat 90.0th-qrtle-23      454.00 (   0.00%)      303.00 (  33.26%)
Lat 99.0th-qrtle-23     3228.00 (   0.00%)     2564.00 (  20.57%)
Lat 99.9th-qrtle-23     5496.00 (   0.00%)     5304.00 (   3.49%)
Lat 20.0th-qrtle-23     3132.00 (   0.00%)     3156.00 (  -0.77%)

Abel Wu (2):
  Revert "sched/fair: Make sched-idle CPU selection consistent throughout"
  sched/fair: Do not specialcase SCHED_IDLE cpus in select slowpath

 kernel/sched/fair.c | 40 ++++++++++++++++++++++++----------------
 1 file changed, 24 insertions(+), 16 deletions(-)

-- 
2.37.3
Re: [RFC PATCH 0/2] Prioritize idle cpus over SCHED_IDLE ones
Posted by Abel Wu 10 months, 3 weeks ago
Ping :)

On 3/10/25 3:40 PM, Abel Wu wrote:
> Since commit
> 
>    17346452b25b ("sched/fair: Make sched-idle CPU selection consistent")
> 
> the SCHED_IDLE cpus are given equal or more preference over idle ones in
> fast- and slow-path of select_task_rq_fair(). This works well in flattened
> cgroup hierarchy, e.g. all tasks running inside root cgroup, but may not
> ideal in a deeper hierarchy where SCHED_IDLE doesn't mean anything between
> entities whose parents are different. Hence a SCHED_IDLE cpu does NOT
> necessarily implies any of the following:
> 
>   - It is a less loaded cpu (since the parent of its topmost idle
>     ancestor could be a 'giant' entity with large cpu.weight).
> 
>   - It can be expected to be preempted by a newly woken task soon
>     enough (which actually depends on their ancestors who have
>     common parent).
> 
> As a less loaded cpu probably has better ability to serve the newly
> woken task, which also applies to the SCHED_IDLE cpus that less loaded
> SCHED_IDLE cpu might be easier and faster preempted, let's not special
> case SCHED_IDLE cpus at least in slowpath when selecting.
> 
>    [ Plan to try the same in SIS, that is selecting a less loaded cpu
>      and get rid of ambiguous sched_idle_cpu(). Comments and suggests
>      are really appreciated. ]
> 
> Some benchmarks are tested in a Intel(R) Xeon(R) CPU E5-2650 v4 machine
> based on tip/master ec3106906cbf, and are tested in following two setup:
> 
> 		(t1)			(t2)
> 		root			root
> 		/  \\			/  \
> 	benchmark   noise	benchmark   X
> 					     \\
> 					     noise
> 
> where noise comes from a SCHED_IDLE cgroup. I didn't see an obvious diff
> in hackbench or tbench, but not schbench.
> 
> 				vanilla-t1	       patched-t1
> Lat 50.0th-qrtle-1         8.00 (   0.00%)        8.00 (   0.00%)
> Lat 90.0th-qrtle-1        13.00 (   0.00%)       13.00 (   0.00%)
> Lat 99.0th-qrtle-1        19.00 (   0.00%)       18.00 (   5.26%)
> Lat 99.9th-qrtle-1        22.00 (   0.00%)       22.00 (   0.00%)
> Lat 20.0th-qrtle-1       257.00 (   0.00%)      259.00 (  -0.78%)
> Lat 50.0th-qrtle-2         8.00 (   0.00%)        9.00 ( -12.50%)
> Lat 90.0th-qrtle-2        13.00 (   0.00%)       13.00 (   0.00%)
> Lat 99.0th-qrtle-2        19.00 (   0.00%)       19.00 (   0.00%)
> Lat 99.9th-qrtle-2        23.00 (   0.00%)       24.00 (  -4.35%)
> Lat 20.0th-qrtle-2       484.00 (   0.00%)      434.00 (  10.33%)
> Lat 50.0th-qrtle-4         9.00 (   0.00%)        9.00 (   0.00%)
> Lat 90.0th-qrtle-4        14.00 (   0.00%)       14.00 (   0.00%)
> Lat 99.0th-qrtle-4        19.00 (   0.00%)       19.00 (   0.00%)
> Lat 99.9th-qrtle-4        25.00 (   0.00%)       24.00 (   4.00%)
> Lat 20.0th-qrtle-4       877.00 (   0.00%)      857.00 (   2.28%)
> Lat 50.0th-qrtle-8         9.00 (   0.00%)        9.00 (   0.00%)
> Lat 90.0th-qrtle-8        14.00 (   0.00%)       15.00 (  -7.14%)
> Lat 99.0th-qrtle-8        20.00 (   0.00%)       21.00 (  -5.00%)
> Lat 99.9th-qrtle-8        26.00 (   0.00%)       26.00 (   0.00%)
> Lat 20.0th-qrtle-8      1698.00 (   0.00%)     1598.00 (   5.89%)
> Lat 50.0th-qrtle-16       10.00 (   0.00%)       10.00 (   0.00%)
> Lat 90.0th-qrtle-16       15.00 (   0.00%)       15.00 (   0.00%)
> Lat 99.0th-qrtle-16       20.00 (   0.00%)       20.00 (   0.00%)
> Lat 99.9th-qrtle-16       28.00 (   0.00%)       27.00 (   3.57%)
> Lat 20.0th-qrtle-16     2900.00 (   0.00%)     2860.00 (   1.38%)
> Lat 50.0th-qrtle-23        9.00 (   0.00%)        9.00 (   0.00%)
> Lat 90.0th-qrtle-23       15.00 (   0.00%)       15.00 (   0.00%)
> Lat 99.0th-qrtle-23       49.00 (   0.00%)       28.00 (  42.86%)
> Lat 99.9th-qrtle-23     1602.00 (   0.00%)     1458.00 (   8.99%)
> Lat 20.0th-qrtle-23     3796.00 (   0.00%)     3804.00 (  -0.21%)
> 
> 				vanilla-t2	       patched-t2
> Lat 50.0th-qrtle-1        10.00 (   0.00%)        9.00 (  10.00%)
> Lat 90.0th-qrtle-1       271.00 (   0.00%)      272.00 (  -0.37%)
> Lat 99.0th-qrtle-1      1013.00 (   0.00%)      793.00 (  21.72%)
> Lat 99.9th-qrtle-1      1998.00 (   0.00%)     1642.00 (  17.82%)
> Lat 20.0th-qrtle-1       262.00 (   0.00%)      262.00 (   0.00%)
> Lat 50.0th-qrtle-2        10.00 (   0.00%)        9.00 (  10.00%)
> Lat 90.0th-qrtle-2       531.00 (   0.00%)      510.00 (   3.95%)
> Lat 99.0th-qrtle-2      1034.00 (   0.00%)      933.00 (   9.77%)
> Lat 99.9th-qrtle-2      1846.00 (   0.00%)     1614.00 (  12.57%)
> Lat 20.0th-qrtle-2       517.00 (   0.00%)      517.00 (   0.00%)
> Lat 50.0th-qrtle-4        10.00 (   0.00%)       10.00 (   0.00%)
> Lat 90.0th-qrtle-4       523.00 (   0.00%)      494.00 (   5.54%)
> Lat 99.0th-qrtle-4       973.00 (   0.00%)      901.00 (   7.40%)
> Lat 99.9th-qrtle-4      1618.00 (   0.00%)     1606.00 (   0.74%)
> Lat 20.0th-qrtle-4      1015.00 (   0.00%)     1001.00 (   1.38%)
> Lat 50.0th-qrtle-8        11.00 (   0.00%)       10.00 (   9.09%)
> Lat 90.0th-qrtle-8       527.00 (   0.00%)      454.00 (  13.85%)
> Lat 99.0th-qrtle-8       931.00 (   0.00%)      901.00 (   3.22%)
> Lat 99.9th-qrtle-8      1598.00 (   0.00%)     1582.00 (   1.00%)
> Lat 20.0th-qrtle-8      1738.00 (   0.00%)     1666.00 (   4.14%)
> Lat 50.0th-qrtle-16        9.00 (   0.00%)        9.00 (   0.00%)
> Lat 90.0th-qrtle-16      410.00 (   0.00%)      243.00 (  40.73%)
> Lat 99.0th-qrtle-16      979.00 (   0.00%)      891.00 (   8.99%)
> Lat 99.9th-qrtle-16     1486.00 (   0.00%)     1470.00 (   1.08%)
> Lat 20.0th-qrtle-16     2708.00 (   0.00%)     2708.00 (   0.00%)
> Lat 50.0th-qrtle-23        8.00 (   0.00%)        9.00 ( -12.50%)
> Lat 90.0th-qrtle-23      454.00 (   0.00%)      303.00 (  33.26%)
> Lat 99.0th-qrtle-23     3228.00 (   0.00%)     2564.00 (  20.57%)
> Lat 99.9th-qrtle-23     5496.00 (   0.00%)     5304.00 (   3.49%)
> Lat 20.0th-qrtle-23     3132.00 (   0.00%)     3156.00 (  -0.77%)
> 
> Abel Wu (2):
>    Revert "sched/fair: Make sched-idle CPU selection consistent throughout"
>    sched/fair: Do not specialcase SCHED_IDLE cpus in select slowpath
> 
>   kernel/sched/fair.c | 40 ++++++++++++++++++++++++----------------
>   1 file changed, 24 insertions(+), 16 deletions(-)
>
Re: [RFC PATCH 0/2] Prioritize idle cpus over SCHED_IDLE ones
Posted by Abel Wu 11 months ago
loop Viresh Kumar

On 3/10/25 3:40 PM, Abel Wu wrote:
> Since commit
> 
>    17346452b25b ("sched/fair: Make sched-idle CPU selection consistent")
> 
> the SCHED_IDLE cpus are given equal or more preference over idle ones in
> fast- and slow-path of select_task_rq_fair(). This works well in flattened
> cgroup hierarchy, e.g. all tasks running inside root cgroup, but may not
> ideal in a deeper hierarchy where SCHED_IDLE doesn't mean anything between
> entities whose parents are different. Hence a SCHED_IDLE cpu does NOT
> necessarily implies any of the following:
> 
>   - It is a less loaded cpu (since the parent of its topmost idle
>     ancestor could be a 'giant' entity with large cpu.weight).
> 
>   - It can be expected to be preempted by a newly woken task soon
>     enough (which actually depends on their ancestors who have
>     common parent).
> 
> As a less loaded cpu probably has better ability to serve the newly
> woken task, which also applies to the SCHED_IDLE cpus that less loaded
> SCHED_IDLE cpu might be easier and faster preempted, let's not special
> case SCHED_IDLE cpus at least in slowpath when selecting.
> 
>    [ Plan to try the same in SIS, that is selecting a less loaded cpu
>      and get rid of ambiguous sched_idle_cpu(). Comments and suggests
>      are really appreciated. ]
> 
> Some benchmarks are tested in a Intel(R) Xeon(R) CPU E5-2650 v4 machine
> based on tip/master ec3106906cbf, and are tested in following two setup:
> 
> 		(t1)			(t2)
> 		root			root
> 		/  \\			/  \
> 	benchmark   noise	benchmark   X
> 					     \\
> 					     noise
> 
> where noise comes from a SCHED_IDLE cgroup. I didn't see an obvious diff
> in hackbench or tbench, but not schbench.
> 
> 				vanilla-t1	       patched-t1
> Lat 50.0th-qrtle-1         8.00 (   0.00%)        8.00 (   0.00%)
> Lat 90.0th-qrtle-1        13.00 (   0.00%)       13.00 (   0.00%)
> Lat 99.0th-qrtle-1        19.00 (   0.00%)       18.00 (   5.26%)
> Lat 99.9th-qrtle-1        22.00 (   0.00%)       22.00 (   0.00%)
> Lat 20.0th-qrtle-1       257.00 (   0.00%)      259.00 (  -0.78%)
> Lat 50.0th-qrtle-2         8.00 (   0.00%)        9.00 ( -12.50%)
> Lat 90.0th-qrtle-2        13.00 (   0.00%)       13.00 (   0.00%)
> Lat 99.0th-qrtle-2        19.00 (   0.00%)       19.00 (   0.00%)
> Lat 99.9th-qrtle-2        23.00 (   0.00%)       24.00 (  -4.35%)
> Lat 20.0th-qrtle-2       484.00 (   0.00%)      434.00 (  10.33%)
> Lat 50.0th-qrtle-4         9.00 (   0.00%)        9.00 (   0.00%)
> Lat 90.0th-qrtle-4        14.00 (   0.00%)       14.00 (   0.00%)
> Lat 99.0th-qrtle-4        19.00 (   0.00%)       19.00 (   0.00%)
> Lat 99.9th-qrtle-4        25.00 (   0.00%)       24.00 (   4.00%)
> Lat 20.0th-qrtle-4       877.00 (   0.00%)      857.00 (   2.28%)
> Lat 50.0th-qrtle-8         9.00 (   0.00%)        9.00 (   0.00%)
> Lat 90.0th-qrtle-8        14.00 (   0.00%)       15.00 (  -7.14%)
> Lat 99.0th-qrtle-8        20.00 (   0.00%)       21.00 (  -5.00%)
> Lat 99.9th-qrtle-8        26.00 (   0.00%)       26.00 (   0.00%)
> Lat 20.0th-qrtle-8      1698.00 (   0.00%)     1598.00 (   5.89%)
> Lat 50.0th-qrtle-16       10.00 (   0.00%)       10.00 (   0.00%)
> Lat 90.0th-qrtle-16       15.00 (   0.00%)       15.00 (   0.00%)
> Lat 99.0th-qrtle-16       20.00 (   0.00%)       20.00 (   0.00%)
> Lat 99.9th-qrtle-16       28.00 (   0.00%)       27.00 (   3.57%)
> Lat 20.0th-qrtle-16     2900.00 (   0.00%)     2860.00 (   1.38%)
> Lat 50.0th-qrtle-23        9.00 (   0.00%)        9.00 (   0.00%)
> Lat 90.0th-qrtle-23       15.00 (   0.00%)       15.00 (   0.00%)
> Lat 99.0th-qrtle-23       49.00 (   0.00%)       28.00 (  42.86%)
> Lat 99.9th-qrtle-23     1602.00 (   0.00%)     1458.00 (   8.99%)
> Lat 20.0th-qrtle-23     3796.00 (   0.00%)     3804.00 (  -0.21%)
> 
> 				vanilla-t2	       patched-t2
> Lat 50.0th-qrtle-1        10.00 (   0.00%)        9.00 (  10.00%)
> Lat 90.0th-qrtle-1       271.00 (   0.00%)      272.00 (  -0.37%)
> Lat 99.0th-qrtle-1      1013.00 (   0.00%)      793.00 (  21.72%)
> Lat 99.9th-qrtle-1      1998.00 (   0.00%)     1642.00 (  17.82%)
> Lat 20.0th-qrtle-1       262.00 (   0.00%)      262.00 (   0.00%)
> Lat 50.0th-qrtle-2        10.00 (   0.00%)        9.00 (  10.00%)
> Lat 90.0th-qrtle-2       531.00 (   0.00%)      510.00 (   3.95%)
> Lat 99.0th-qrtle-2      1034.00 (   0.00%)      933.00 (   9.77%)
> Lat 99.9th-qrtle-2      1846.00 (   0.00%)     1614.00 (  12.57%)
> Lat 20.0th-qrtle-2       517.00 (   0.00%)      517.00 (   0.00%)
> Lat 50.0th-qrtle-4        10.00 (   0.00%)       10.00 (   0.00%)
> Lat 90.0th-qrtle-4       523.00 (   0.00%)      494.00 (   5.54%)
> Lat 99.0th-qrtle-4       973.00 (   0.00%)      901.00 (   7.40%)
> Lat 99.9th-qrtle-4      1618.00 (   0.00%)     1606.00 (   0.74%)
> Lat 20.0th-qrtle-4      1015.00 (   0.00%)     1001.00 (   1.38%)
> Lat 50.0th-qrtle-8        11.00 (   0.00%)       10.00 (   9.09%)
> Lat 90.0th-qrtle-8       527.00 (   0.00%)      454.00 (  13.85%)
> Lat 99.0th-qrtle-8       931.00 (   0.00%)      901.00 (   3.22%)
> Lat 99.9th-qrtle-8      1598.00 (   0.00%)     1582.00 (   1.00%)
> Lat 20.0th-qrtle-8      1738.00 (   0.00%)     1666.00 (   4.14%)
> Lat 50.0th-qrtle-16        9.00 (   0.00%)        9.00 (   0.00%)
> Lat 90.0th-qrtle-16      410.00 (   0.00%)      243.00 (  40.73%)
> Lat 99.0th-qrtle-16      979.00 (   0.00%)      891.00 (   8.99%)
> Lat 99.9th-qrtle-16     1486.00 (   0.00%)     1470.00 (   1.08%)
> Lat 20.0th-qrtle-16     2708.00 (   0.00%)     2708.00 (   0.00%)
> Lat 50.0th-qrtle-23        8.00 (   0.00%)        9.00 ( -12.50%)
> Lat 90.0th-qrtle-23      454.00 (   0.00%)      303.00 (  33.26%)
> Lat 99.0th-qrtle-23     3228.00 (   0.00%)     2564.00 (  20.57%)
> Lat 99.9th-qrtle-23     5496.00 (   0.00%)     5304.00 (   3.49%)
> Lat 20.0th-qrtle-23     3132.00 (   0.00%)     3156.00 (  -0.77%)
> 
> Abel Wu (2):
>    Revert "sched/fair: Make sched-idle CPU selection consistent throughout"
>    sched/fair: Do not specialcase SCHED_IDLE cpus in select slowpath
> 
>   kernel/sched/fair.c | 40 ++++++++++++++++++++++++----------------
>   1 file changed, 24 insertions(+), 16 deletions(-)
>