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It doesn't provide any advantages because there is no install base, so desktop software doesn't utilize it. It's just a wider SIMD instruction set, and I'm conf
by nullifidian 5y ago
It doesn't provide any advantages because there is no install base, so desktop software doesn't utilize it. It's just a wider SIMD instruction set, and I'm confused why people relegate it to HPC only category.
- CodesInChaos 5y agoAFAIK it downclocks the CPU, even if the AVX512 instructions are only a tiny fraction of instructions. So you only benefit from AVX512 if you use it enough. While 128 bit SIMD give you a speedup if you use it for a few functions that need it, without slowing down the rest of your code or even unrelated applications.
- nullifidian 5y agoIn heavily vectorized applications you still get a sizable speed up over AVX2, e.g. in tasks like video encoding. In mixed/real-time applications this issue could be solved by dedicating/pinning a thread with the AVX-512 payload to a core, automatically or manually. Not sure if such policies have been implemented in practice.
- dragontamer 5y agoThere's significant downclocking only on on Skylake-X (aka: 1st generation teething problems). On more recent cores, there's only ~100 MHz of downclocking, which is so small you can pretty much ignore it.
- jeffbee 5y agoIt's amazing how sticky the myth has become, though. On Ice Lake Xeon there is basically no penalty for using the AVX-512 unit.
- dragontamer 5y agoIt was true for several years, because Intel got "stuck" on Skylake due to issues in their manufacturing. If Intel was able to get Icelake out on time, it may have reduced the "stickiness" of the myth.
- jeffbee 5y agoTrue. But the power penalty from 512 was already quite reduced in Cannon Lake (2018) and completely gone in Tiger Lake (2020).