Preemptive Multitasking

Preemptive Multitasking

A multitasking method that shares processing time with all running programs. Preemptive multitasking creates a time-shared environment in which running programs get a recurring slice of time from the CPU. Depending on the operating system, the time slice may be the same for all programs or it may be adjustable to meet the current mix of programs and users. For example, background programs can be given more CPU time no matter how heavy the foreground load and vice versa. Preemptive multitasking is vital in a mainframe, but is also useful in a desktop operating system. For example, it ensures that data will not be lost if a transmission is taking place in the background. The OS is able to grab the machine cycles that the modem or network program needs to continue processing the incoming data stream.

Non-Preemptive Multitasking

A multitasking environment in which an application is able to give up control of the CPU to another application only at certain points, such