Operating System – Memory Management and Scheduling

1- When a process terminates, it may own a number of pages in memory that have the Dirty-Bit set. What should be done with this pages? 2- Consider a system with segmentation (no paging) Two process, p1 and p2, are currently running. Their respective segment tables have the following contents: (the number represents the memory location where the segment is loaded) a- Which segments are shared? b-Which of the following virtual addresses would be illegal in the segment at location 6000: (x,y) represents the logical address (segment,displacement) (0,0) (1,0) (2,0) process 1 4000 … 6000 … 9000 … 2000 … 7000 … process 2 2000 … 6000 … 9000 … (3,0) (4,0) (5,0) c-The segment at location 7000 is swapped out and relocated at 8000. Similarly ,segment at location 2000 is swapped out and relocated at 1000. Show the new segment tables. 3-Consider a system using Round-Robin scheduling with a fixed quantum q. Every context switch tales s milliseconds. Any given process runs on the average of t milliseconds before it blocks or terminates. a-Determine the fraction of CPU time that will be wasted because of context switching for each of the following cases: a- t < q ii) b- t >> q (i.e., t is much greater than q ) c- q approaches 0 d- Under what condition will the wasted fraction of CPU time be exactly 50% ? 4- On a system using multilevel feedback queues, a totally CPU-bound process requires 50 seconds to execute. If the first queue uses a time quantum of 5 seconds, and at each lower level the time quantum doubles, how many times will the process be interrupted and from what queue was the process scheduled when it terminates?