Other BOLT weirdness

Posted Oct 27, 2024 5:57 UTC (Sun) by Cyberax (✭ supporter ✭, #52523)
In reply to: Other BOLT weirdness by kmeyer
Parent article: Kernel optimization with BOLT

> You can use runtime cpuid feature bit detection and identify the running CPU supports AVX512

AVX-512 is stupid. It doesn't work on efficiency cores on Alder Lake. Even though P-cores support it.

Other BOLT weirdness

Posted Oct 27, 2024 6:59 UTC (Sun) by intelfx (subscriber, #130118) [Link]

> AVX-512 is stupid. It doesn't work on efficiency cores on Alder Lake

Perhaps it rather means that Alder Lake is stupid?

Other BOLT weirdness

Posted Nov 1, 2024 18:20 UTC (Fri) by anton (subscriber, #25547) [Link]

The P-cores of Alder Lake don't support AVX-512 (implemented but disabled), either, unless you are using some early firmware. It's a pity that Intel completely disabled that, even in Xeon-E24xx CPUs where the E-cores are disabled. But don't worry, buy an AMD CPU with a Zen4 or Zen5 core, and you will get AVX-512.