CPU I/O Burst Cycle:
The execution of a process consists of an alternation of CPU bursts and I/O bursts. A process begins and ends with a CPU burst. In between, CPU activity is suspended whenever an I/O operation is needed.
If the CPU bursts are relatively short compared to the I/O bursts, then the process is said to be I/O bound. For example, a typical data processing task involves reading a record, some minimal computation and writing a record.
If CPU bursts are relatively long compared to I/O bursts, a process is said to be CPU bound. A number crunching task involves an I/O burst to read parameters. A very long CPU burst and another I/O burst is required to write results.
