CSE 131 Lecture Notes - Lecture 9: Job Scheduler, Child Process, First Come, First Served
Document Summary
At the time they enter the system. Submission of a new job causes the scheduler to run. Scheduling only done when a job voluntarily gives up the cpu (i. e. while waiting for an i/o request) May also be used for batch systems. Scheduling algorithms at each interrupt and picks the next process from the pool of ready processes. When are processes scheduled: when a process is created. A fork creates a parent and child processes. The scheduler picks one (they are both in the ready state: when a process exits. Picks a ready process: when a process blocks on i/o, lock, or other. The type of block can influence which process to wake. E. g. blocking on a semaphore may cause switching to the process in the critical region: when an interrupt occurs. E. g. an i/o is complete and thus promoting waking up a process waiting for the input. A periodic clock interrupt can cause rescheduling (non) preemptive scheduling algorithms.
