Intel Core i9 12900K "Alder Lake" AVX-512 On Linux
Written by Michael Larabel in Processors on 7 November 2021. Page 1 of 2. 88 Comments

While it was initially communicated by Intel that Alder Lake's Golden Cove P-Cores has AVX-512 "fused off", that has turned out not to be the case at least with the initial batch of processors and current BIOS/firmware configurations. If disabling the power-efficient Gracemont E-Cores, it's possible to enable AVX-512 and make use of it. Here are some initial AVX-512 benchmarks in such a configuration under Linux with the Core i9 12900K.

One of the odd transitions with Alder Lake is that while prior generation Rocket Lake featured AVX-512 on the desktop, going to Alder Lake with the new hybrid architecture meant no (official) AVX-512 support with the mix of high performance and power efficient cores. But as it turns out, at least with the initial Alder Lake processors and prior to any new BIOS/firmware updates, AVX-512 can be happily enabled for the high performance cores.

With the initial public 0702 BIOS for the ASUS STRIX Z690-E GAMING WiFi motherboard and the Core i9 12900K sample received from Intel, if disabling all of the E cores from the BIOS and then setting the AVX-512 option from "Auto" to "Enabled", will actually enable AVX-512.

In this configuration, avx512f, avx512dq, avx512ifma, avx512cd, avx512bw, avx512vl, avx512_bf16, avx512vbmi, avx512_vbmi2, avx512_vnni, avx512_bitalg, avx512_vpopcntdq, avx512_vp2intersect, and avx512_fp16 were exposed and working under Linux.

For some weekend benchmarks I focused in on some AVX-512 friendly mining tests of the Core i9 12900K in its stock configuration (16 cores / 24 threads), the i9-12900K with only P-cores enabled (8 cores / 16 threads), and then that same P-core-only configuration but enabling AVX-512. Then from the Phoronix Test Suite I fired up some benchmarks while also monitoring the Alder Lake thermals and power consumption.

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