Timing Ballpark Figures

Internet ping messages usually take on the order of ms to tens of ms for a good connection, hundreds of ms if something is really clogged.

Inter-core messaging on an RTOS in a multi-core device running at hundreds of Mhz could be on the order of us (microseconds).

1 Ghz = 1 ns clock cycle
100 Mhz = 10 ns clock cycle
1 MHz = 1000 ns or 1us clock cycle
100 KHz = 10 us clock cycle

State Machines

State machines and time slicing are two popular multitasking methods. State machines have been used to design complex systems with high reliability requirements. State machines require that the task is split into states. The state machine stays in one state at a time, and switches to another state when specified conditions are met. Actions are performed during the transitions. States represent a situation that is stable for some time interval. Time slicing means that the kernel interrupts each process after some milliseconds and gives control to another task. Thus, each task is given CPU processing at regular intervals.