True parallelism on PS

I checked /proc/cpuinfo on my PS and it reported that 4 CPUs (cores) were available. I don’t necessarily trust that, though. Do PSes get true native parallelism, that is the ability to have 4 active threads across the system at the same time?

If so, and I have my PS set to 1GHz, does that mean CPU accounting gives me 1 GHz guaranteed on each CPU (theoretical 4GHz total), or 1 GHz total?