CPU Clocks and Clock Interrupts, and Their Effects on Schedulers (2015)

The slope of the rise and fall of the clock is usually exaggerated in these diagrams to make it easy to see; there often are other lines superimposed on the clock signal to indicate logic level hysteresis and timing. In a multi-process and/or multi-threaded environment the scheduler is responsible for allocating this limited CPU resource, temporarily suspending the execution of one process and/or thread, and temporarily resuming the execution of a different process and/or thread. A time-sharing scheduler allocates CPU time on a round-robin basis, where each process gets a certain fraction of the available CPU time.

Source: accu.org