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**Re: Homework question 5.7 makes no sense.**

**To**:**class-cs411@engr.orst.edu, richarle@engr.orst.edu****Subject**:**Re: Homework question 5.7 makes no sense.****From**:**Cherri Pancake <pancake@nacse.org>****Date**: Thu, 15 Apr 1999 17:31:24 -0700 (PDT)

this does not say that A and B are positive. A and B are rates of change. In (a), both cause a process's priority to increase from zero. In (b) they both cause a process's priority to decrease from zero. (Note that all start at zero.) ============================= yournote ============================ 5.7 Consider the following preemptive priority-scheduling algorithm based on dynamically changing priorities. Larger priority numbers imply6 higher priority. When a process is waiting for the CPU (in the ready queue, but not running), its priority changes at rate A; when it is running, its priority changes at rate B. All processes are given a priority of 0 when they enter the ready queue. The parameters A and B can be set to give many different scheduling algorithms. a. What is the algorithm that results from B > A > 0? b. What is the algorithm that results from A < B < 0? The first thing that strikes me as strange is that A and B are both positive. Normally, in this type of system, A is positive and B is negative. The priority for a process is normally >= 0. I ran through these processes setting B=2 and A=1 (for a.) and this is the order I saw for three processes one unit apart: 11122112331221... What algorithm does this fit? Question b. came out as LIFO. I am confused. Roy

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