8. Scheduling: MLFQ Flashcards
What is the problem that MLFQ tries to solve?
How to optimize for both turnaround and response time without knowing a job length.
What is principle behind MLFQ?
MLFQ has a number of distinct queue and scheduler runs jobs that are on higher queue first.
Scheduler varies processes’ priority based on past behavior.
How does MLFQ approximates SJF?
It assumes that any jobs that comes in is a short job, so it will put it into highest priority and gradually move down to lower queues if the job does not finish in given time slice
What is a starvation problem and how does MLFQ solve it?
Starvation problem is when only short jobs alternate between each other without giving long-running jobs a CPU. The problem is solved by periodically boosting job’s priority.
What is an issue of MLFQ?
Presence of voodo constants such as number of queues, time slices and peroidicity of boost
What is a gaming scheduler problem? How is it solved?
It’s a problem where a process would issue an I/O request before using the time slice so it remains on the topmost queue. The issue is solved by accounting for the time slice the process used regardless of how many times it has given up the CPU.
