Comment 17 for bug 1869990

What if instead of visiting each cpu individually, you visit by numa node and only consider thread grouping inside a numa node? Then you could go back to the old datastructure. You could also fall back to visiting by cpu directly if the node interface doesn't exist:

user@host:~# ls -salh /sys/devices/system/node/node*/cpu*
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node0/cpu0 -> ../../cpu/cpu0
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node0/cpu1 -> ../../cpu/cpu1
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node0/cpu2 -> ../../cpu/cpu2
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node0/cpu3 -> ../../cpu/cpu3
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node0/cpu4 -> ../../cpu/cpu4
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node0/cpu5 -> ../../cpu/cpu5
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node0/cpu6 -> ../../cpu/cpu6
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node0/cpu7 -> ../../cpu/cpu7
0 -r--r--r-- 1 root root 4.0K Apr 2 01:10 /sys/devices/system/node/node0/cpulist
0 -r--r--r-- 1 root root 4.0K Apr 2 00:42 /sys/devices/system/node/node0/cpumap
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node1/cpu10 -> ../../cpu/cpu10
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node1/cpu11 -> ../../cpu/cpu11
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node1/cpu12 -> ../../cpu/cpu12
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node1/cpu13 -> ../../cpu/cpu13
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node1/cpu14 -> ../../cpu/cpu14
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node1/cpu15 -> ../../cpu/cpu15
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node1/cpu8 -> ../../cpu/cpu8
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node1/cpu9 -> ../../cpu/cpu9
0 -r--r--r-- 1 root root 4.0K Apr 2 01:10 /sys/devices/system/node/node1/cpulist
0 -r--r--r-- 1 root root 4.0K Apr 2 00:42 /sys/devices/system/node/node1/cpumap
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node2/cpu16 -> ../../cpu/cpu16
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node2/cpu17 -> ../../cpu/cpu17
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node2/cpu18 -> ../../cpu/cpu18
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node2/cpu19 -> ../../cpu/cpu19
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node2/cpu20 -> ../../cpu/cpu20
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node2/cpu21 -> ../../cpu/cpu21
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node2/cpu22 -> ../../cpu/cpu22
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node2/cpu23 -> ../../cpu/cpu23
0 -r--r--r-- 1 root root 4.0K Apr 2 01:10 /sys/devices/system/node/node2/cpulist
0 -r--r--r-- 1 root root 4.0K Apr 2 00:42 /sys/devices/system/node/node2/cpumap
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node3/cpu24 -> ../../cpu/cpu24
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node3/cpu25 -> ../../cpu/cpu25
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node3/cpu26 -> ../../cpu/cpu26
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node3/cpu27 -> ../../cpu/cpu27
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node3/cpu28 -> ../../cpu/cpu28
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node3/cpu29 -> ../../cpu/cpu29
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node3/cpu30 -> ../../cpu/cpu30
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node3/cpu31 -> ../../cpu/cpu31
0 -r--r--r-- 1 root root 4.0K Apr 2 01:10 /sys/devices/system/node/node3/cpulist
0 -r--r--r-- 1 root root 4.0K Apr 2 00:42 /sys/devices/system/node/node3/cpumap
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node4/cpu32 -> ../../cpu/cpu32
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node4/cpu33 -> ../../cpu/cpu33
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node4/cpu34 -> ../../cpu/cpu34
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node4/cpu35 -> ../../cpu/cpu35
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node4/cpu36 -> ../../cpu/cpu36
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node4/cpu37 -> ../../cpu/cpu37
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node4/cpu38 -> ../../cpu/cpu38
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node4/cpu39 -> ../../cpu/cpu39
0 -r--r--r-- 1 root root 4.0K Apr 2 01:10 /sys/devices/system/node/node4/cpulist
0 -r--r--r-- 1 root root 4.0K Apr 2 00:42 /sys/devices/system/node/node4/cpumap
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node5/cpu40 -> ../../cpu/cpu40
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node5/cpu41 -> ../../cpu/cpu41
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node5/cpu42 -> ../../cpu/cpu42
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node5/cpu43 -> ../../cpu/cpu43
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node5/cpu44 -> ../../cpu/cpu44
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node5/cpu45 -> ../../cpu/cpu45
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node5/cpu46 -> ../../cpu/cpu46
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node5/cpu47 -> ../../cpu/cpu47
0 -r--r--r-- 1 root root 4.0K Apr 2 01:10 /sys/devices/system/node/node5/cpulist
0 -r--r--r-- 1 root root 4.0K Apr 2 00:42 /sys/devices/system/node/node5/cpumap
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node6/cpu48 -> ../../cpu/cpu48
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node6/cpu49 -> ../../cpu/cpu49
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node6/cpu50 -> ../../cpu/cpu50
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node6/cpu51 -> ../../cpu/cpu51
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node6/cpu52 -> ../../cpu/cpu52
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node6/cpu53 -> ../../cpu/cpu53
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node6/cpu54 -> ../../cpu/cpu54
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node6/cpu55 -> ../../cpu/cpu55
0 -r--r--r-- 1 root root 4.0K Apr 2 01:10 /sys/devices/system/node/node6/cpulist
0 -r--r--r-- 1 root root 4.0K Apr 2 00:42 /sys/devices/system/node/node6/cpumap
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node7/cpu56 -> ../../cpu/cpu56
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node7/cpu57 -> ../../cpu/cpu57
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node7/cpu58 -> ../../cpu/cpu58
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node7/cpu59 -> ../../cpu/cpu59
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node7/cpu60 -> ../../cpu/cpu60
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node7/cpu61 -> ../../cpu/cpu61
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node7/cpu62 -> ../../cpu/cpu62
0 lrwxrwxrwx 1 root root 0 Apr 2 01:10 /sys/devices/system/node/node7/cpu63 -> ../../cpu/cpu63
0 -r--r--r-- 1 root root 4.0K Apr 2 01:10 /sys/devices/system/node/node7/cpulist
0 -r--r--r-- 1 root root 4.0K Apr 2 00:42 /sys/devices/system/node/node7/cpumap