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Isn't Zen 2 adding support for AVX512?
by pythonaut_16 8y ago
Isn't Zen 2 adding support for AVX512?
- bitL 8y agoYes, 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.
- bpye 8y agoDoesn'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-frequency-scaling/ https://blog.cloudflare.com/on-the-dangers-of-intels-frequen...
- gameswithgo 8y agoAVX and AVX512 both do downclocking. Likely AMD will have to downclock too, pretty fundamental limits at work there.
- bitL 8y agoWith 7nm they might not need to downclock that much.
- hajile 8y agoAMD 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-an-interview-with-amd-cto-mark-papermaster 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/specification-updates/xeon-scalable-spec-update.pdf https://www.intel.com/content/dam/www/public/us/en/documents...
- paulmd 8y agoAVX-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.
- dragontamer 8y agoCitation please. I never heard of Zen2 supporting AVX512.