Consider four process all are arriving at time zero, with total execution time of 20, 10, 10 and 20 unit respectively. Each process spends the first 20% of execution time doing CPU, the next 60%of doing IO computation and the last 20% of time doing CPU computation again. The operating system uses longest time remaining first scheduling algorithm (LRTF) and schedules a new process either when running process get blocked IO or when the running process finishes its CPU burst. Assume that are I/O operations can be overlapped as much as possible. What is the completion time of process P0? [Note: When same burst occurs for multiple process high priority given to lowest process id].
- 18
- 20
- 24
- 28
I am getting 20 as answer if I schedule based only on
schedules a new process either when running process get blocked IO or when the running process finishes its CPU burst.