The lock is top of the profile when applied to kernel with other patches (will post later):
```
294846572 (spin mutex:callout)
1832520 (sleep mutex:TID lock)
```
disappears afterwards. bumps thread creation/destruction rate 2 -> 3 mln ops/s with 104 workers doing it.
```
commit 885ad80eaa83261a32815a4f5ec094d35cd5b620
Author: Mateusz Guzik <mjg@FreeBSD.org>
Date: Thu Aug 25 22:42:42 2022 +0000
thread: use callout_init_cpu(..., curcpu)
Sorts out callout lock contention during heavy thread
creation/destruction test.
Reviewed by:
Differential Revision:
commit fdd578e33ad1be7410ad5384b0e22ab351fb0803
Author: Mateusz Guzik <mjg@FreeBSD.org>
Date: Thu Aug 25 22:42:08 2022 +0000
callout: add callout_init_cpu
Reviewed by:
Differential Revision:
```