I have an old-ish but still relatively powerful server with 2 6-core CPUs with 2 threads per core, so 24 threads total.
Sometimes the corewrapper gets started with -np 23 instead of 24, although the number of CPUs is configured as "-1": "use as many as possible". Performance is also set to "full", or "100%", so it should use all of the cores. I explicitly disabled GPU folding; the machine has no GPU.
It tells me:
Code: Select all
WARNING:WU00:FS00:AS lowered CPUs from 24 to 23
Now 23 threads is rejected because it is prime, and 22 is rejected because it has a large prime factor, so the core proper is started with "only" 21 threads. It is still fine, it is not a large reduction in performance, but it seems that it should be running on 24 cores, and sometimes does, but not at other times.
I do all configuration with command-line options, and don't use any graphical control frontend for various reasons.
Maybe this has been asked before, but I cannot search for it: "24" and "23" are rejected as search terms, because they are too short.
Cheers,
HG.