Multithreaded Programming Guide

Fair Share Scheduling

The fair share scheduler (FSS) scheduling class allows allocation of CPU time based on shares.

By default, the FSS scheduling class uses the same range of priorities (0 to 59) as the TS and interactive (IA) scheduling classes. All LWPs in a process must run in the same scheduling class. The FSS class schedules individual LWPs, not whole processes. Thus, a mix of processes in the FSS and TS/IA classes could result in unexpected scheduling behavior in both cases.

With the use of processor sets, you can mix TS/IA with FSS in one system as long as all the processes running on each processor set are in either the TS/IA or the FSS scheduling class, so they do not compete for the same CPUs.