For me today it's definitely a pessimation because I have enough well-meaning applications that spawn `nproc` worker threads. Which would be fine if they're the only process running, but they're not.

I wrote a little tool for our services that could do basic expression based off of nproc based on an environment variable at startup time.

You could do one thread for every two cores, three threads for every 2 cores, one thread per core ± 1, or both (2n + 1).

Unfortunately the sweet spot based on our memory usage always came out to 1:1, except for a while when we had a memory leak that was surprisingly hard to fix, and we ran n - 1 for about 4 months while a bunch of work and exploratory testing were done. We had to tune in other places to maximize throughput.

Wouldn't that be about the same badness without hyperthreads? If you're oversubscribed, there might be some benefit to having fewer tasks, but maybe you get some good throughput with two different application's threads running on opposite hyperthreads.