5 ms·

Remember that bug with Intel Skylakes [0]? When an application used AVX, it slowed down everything else on that node. It was by far not easy to debug why some a

by d5lt5 2mo ago

Remember that bug with Intel Skylakes [0]? When an application used AVX, it slowed down everything else on that node. It was by far not easy to debug why some applications randomly suffered perf hits on a new hardware being rolled out in Azure. [0] https://arxiv.org/abs/1901.04982?utm_source=chatgpt.com https://arxiv.org/abs/1901.04982?utm_source=chatgpt.com

p_l 2mo ago
It was an early AVX-512 unit that resulted in down lock when you used more than a few instructions in short time, as well as resulted in a Linus rant. Later CPUs (updated skylake xeons and later, AMD Zen 4 and newer) don't have the issue
- e4m2 2mo ago
  Historically, it was a bit more complex than that, and applies to more than just AVX-512: https://gist.github.com/rygorous/32bc3ea8301dba09358fd2c64e02d774 https://gist.github.com/rygorous/32bc3ea8301dba09358fd2c64e0....
  - p_l 2mo ago
    Fun! in Dwarf Fortress way :) Thanks for the deeper dive
adrian_b 2mo ago
The Intel server CPUs Skylake Server, Cascade Lake and Cooper Lake, which had bad frequency/voltage management are now ancient history and very few of them have been used as workstation CPUs by individual users. AMD Zen 4 and Zen 5, and also those Intel CPUs with AVX-512 support starting with Ice Lake, behave much better and there is no reason to avoid AVX-512, which has much better energy efficiency than the alternatives.
- d5lt5 2mo ago
  "Those who cannot remember the past are condemned to repeat it."