The 4BSD process scheduler in the FreeBSD kernel performs scheduling based on CPU billing gathered from periodic process sampling ticks, which allows local users to cause a denial of service (CPU consumption) by performing voluntary nanosecond sleeps that result in the process not being active during a clock interrupt, as described in "Secretly Monopolizing the CPU Without Superuser Privileges."
| Software | From | Fixed in |
|---|---|---|
| freebsd / freebsd | - | - |