Mechanism to detect performance CPU core is not reliable

[ykhrustalev]

🐛 Describe the bug

When running the code

executorch::extension::cpuinfo::get_num_performant_cores()

It will report all cores in some cases, in particular

• Apple iPhone 14
• Pixel8

Versions

None

cc @larryliu0820 @manuelcandales

[tarun292]

@kimishpatel @digantdesai @swolchok any thoughts on this?

[kimishpatel]

For iphone i had internal commits that need to be upstreamed. We should fix this directly in cpuinfo.

For pixel8 I will look into it

[digantdesai]

yeah IIRC on the newer pixels the topology files are not what cpuinfo expects
i.e. /sys/devices/system/cpu/cpu*/topology/cluster_cpus_list

Do you want to create an issue on pytorch/cpuinfo and assign it to me?

I see @kimishpatel 's iphone detection PR in cpuinfo - we need to merge that as well.

[ykhrustalev]

@digantdesai pytorch/cpuinfo#293

[kimishpatel]

@ykhrustalev #11268 should fix it after cpuinfo patch landed. Can you try and close the issue if it works

[ykhrustalev]

thanks @kimishpatel