Originally posted by lucasbekker
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Originally posted by lucasbekker
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Here's the worst-case scenario, for AVX-512: https://blog.cloudflare.com/on-the-d...uency-scaling/
Intel screwed themselves by getting ahead of what the process technology could support. Just like they did with AVX2, except worse. Dropping the CPU from a base clock of 2.1 GHz to 1.4 is just not forgivable! Especially when you're just executing 512-bit instructions for a small % of the time!
The only time AVX-512 is a net win (performance-wise, not even to speak of pref/W) is when your workload is using it very heavily. That's why Torvalds was complaining about the possibility of some idiot using it for memcpy().
Now, my hope and expectation is for Ice Lake SP (and maybe even Rocket Lake) to exercise more care and less latency around clock-speed adjustments, so that it wouldn't be a liability. However, I have yet to see good data on whether Intel managed to effectively mitigate the performance pitfalls of moderate AVX-512 usage, in Ice Lake (or Rocket Lake).
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