MULTILEVEL QUEVE :

Several queues arranged in some priority order.
Each queue could have a different scheduling discipline/ time quantum.
Lower quanta for higher priorities generally.
Defined by:

• # of queues
• scheduling algo for each queue
• when to upgrade a priority
• when to demote

Attacks both efficiency and response time problems.

• Give newly runnable process a high priority and a very short time slice. If process uses up the time slice without blocking then decrease priority by 1 and double its next time slice.
• Often implemented by having a separate queue for each priority.

How are priorities raised? By 1 if it doesn't use time slice? What happens to a process that does a lot of computation when it starts, then waits for user input? Need to boost priority a lot, quickly.