Taos is intended for use in environments with responsible users and plenty of resources (e.g., disk space and processor cycles). Therefore it was decided that it wasn't important to provide much support for resource allocation or accounting.
Taos does not implement disk quotas; the quota and setquota kernel calls always raise SIGSYS.
Taos, unlike Ultrix, does not reserve extra space on each volume for use only by the super-user (see the minfree parameter in mkfs(8)).
Only some of the resource limits associated with the getrlimit and setrlimit kernel calls are implemented, namely data, stack, and core. The other limits, namely cpu, fsize, and rss, are not implemented: setrlimit no-ops and getrlimit returns 0x7fffffff as both the hard and soft limit.
Most of the resource usage information returned by the getrusage and wait3 kernel calls is always zero; only the user time and system time are maintained.
Taos does not implement the accounting file; the acct kernel call always raises SIGSYS.
The Ultrix ps command doesn't run on Taos because it depends on /dev/kmem; for an alternative, see si(1).
On Taos, the virtual and profiling interval timers are quite expensive to use; the real interval timer is not.