Default scheduler processing of migrated workloads

The division between processes and threads is invisible to existing programs.

In fact, workloads migrated directly from earlier releases of the operating system create processes as they have always done. Each new process is created with a single thread (the initial thread) that contends for the CPU with the threads of other processes.

The default attributes of the initial thread, in conjunction with the new scheduler algorithms, minimize changes in system dynamics for unchanged workloads.

Priorities can be manipulated with the nice and renice commands and the setpri() and setpriority() system calls, as before. The scheduler allows a given thread to run for at most one time slice (normally 10 ms) before forcing it to yield to the next dispatchable thread of the same or higher priority. See Controlling contention for the microprocessor for more detail.