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Computer multitasking - Wikipedia, the free encyclopedia (1478 words) |
 | Multitasking solves the problem by scheduling which task may be the one running at any given time, and when another waiting task gets a turn. |
| Another reason for multitasking was in the design of real-time computing systems, where a number of possibly unrelated external activities needed to be controlled by a single processor system. |
| Typically, a multitasking system allows another process to run when the running process hits a point where it has to wait for some portion of memory to be reloaded from secondary storage. |
| multitasking from FOLDOC (360 words) |
| Under "cooperative multitasking" the running task decides when to give up the CPU and under "pre-emptive multitasking" (probably more common) a system process called the "scheduler" suspends the currently running task after it has run for a fixed period known as a "time-slice". |
| Multitasking introduces overheads because the processor spends some time in choosing the next job to run and in saving and restoring tasks' state, but it reduces the worst-case time from job submission to completion compared with a simple batch system where each job must finish before the next one starts. |
| Multitasking also means that while one task is waiting for some external event, the CPU to do useful work on other tasks. |
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