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Comment by pythonaut_16 | Hacker News Reader

Isn't Zen 2 adding support for AVX512?

Yes, but a slow one. They just bump AVX units from 128-bit to 256-bit, making it Haswell-style. Skylake-X has a full 512-bit wide AVX unit.

Doesn't Skylake-X have the whole downclocking issue when running AVX-512 workloads though? Unless you can use almost exclusively AVX-512 then it doesn't make sense.

https://blog.cloudflare.com/on-the-dangers-of-intels-frequen...

AVX and AVX512 both do downclocking. Likely AMD will have to downclock too, pretty fundamental limits at work there.

With 7nm they might not need to downclock that much.

AMD verified they would be running AVX2 at full clocks. Doing AVX-512 would happen at half-rate, but the processor would continue at full speed. In contrast, skylake downclocks base clocks by 30+%.

Not only does the AVX calculation downclock, but all the other calculations in other ALUs/FPUs also downclock. For pure AVX-512 workloads, Intel would be a little faster, but for mixed loads, AMD should be much faster overall.

AMD says they don't downclock AVX2 (about 2/5 down the page)

https://www.anandtech.com/show/13578/naples-rome-milan-zen-4...

See page 13 for AVX clockspeeds

https://www.intel.com/content/dam/www/public/us/en/documents...

AVX-512 isn't just a wider vector, it also fills in some holes in the AVX instruction sets. It's still useful to support it, even if they are only doing it at AVX2 throughput levels.

Citation please. I never heard of Zen2 supporting AVX512.

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