All processes run on only one CPU

Hi,

I've noticed this behavior happening sometimes in the past, where 
processes and their children sometimes don't use both CPUs in a dual 
processor AlphaServer DS25. Both processors could be used by running 
multiple different things, usually.

On 10.1_STABLE from mid June 2025, it seems there is no occasional stuff 
on both CPUs. Running two totally separate sets of tasks, I see:

load averages:  5.99,  5.94,  5.89;               up 66+08:59:48   23:19:
78 processes: 6 runnable, 54 sleeping, 17 stopped, 1 on CPU
CPU:  0.0% user, 47.0% nice,  3.0% system,  0.1% interrupt, 49.8% idle
Memory: 5276M Act, 3033M Inact, 14M Wired, 184M Exec, 7003M File, 941M Fr
Swap: 24G Total, 16M Used, 24G Free / Pools: 2774M Used / Network: 20K In

   PID USERNAME PRI NICE   SIZE   RES STATE       TIME   WCPU    CPU COMMA
   446 root      23    4   111M   92M RUN/0       0:23 16.27% 16.26% cc1pl
  1325 root      23    4   122M   97M RUN/0       0:22 14.90% 14.89% cc1pl
  2260 root      23    4   137M  120M RUN/0       1:37 14.84% 14.84% cc1pl
  9123 root      24    4   170M  153M RUN/0       0:12 15.10% 14.79% cc1pl
28331 root      23    4   148M  129M RUN/0       0:08 15.12% 14.16% cc1pl
21158 root      24    4   118M   96M RUN/0       0:05 15.17% 12.11% cc1pl
     0 root     124    0     0K 1693M syncer/0   71.1H  0.00%  0.00% [syst
  2386 john      85    0    12M 6096K kqueue/1   89:14  0.00%  0.00% tmux


I can force everything to the other CPU with cpuctl offline 0. I can force 
them back. I can move everything to processor 1, then psrset -u one of the 
processes, and it will run on processor 0 to completion, but I have no 
idea why processes won't run on both processors automatically.

Anyone?

Thanks,
John