1. Two processes, A and B, each need three resources, 1, 2, and 3. Suppose A requests them in the order 1, 2, 3. If B also requests them in the same order, deadlock is not possible. However, if B requests them in the order 3, 2, 1, then deadlock is possible. With three resources, there are 3! or six possible orders in which B can request them. For each possible order in which B can request these resources, state whether or not a deadlock is possible for that order. (Assume that once a process acquires a resource, it does not release that resource until the end of that process.) a) 1, 2, 3 b) 1,3,2 c) 2, 1, 3 d) 2, 3, 1 e) 3, 1, 2 f) 3, 2, 1

1. Two processes, A and B, each need three resources, 1, 2, and 3. Suppose A requests them in the order 1, 2, 3. If B also requests them in the same order, deadlock is not possible. However, if B requests them in the order 3, 2, 1, then deadlock is possible. With three resources, there are 3! or six possible orders in which B can request them. For each possible order in which B can request these resources, state whether or not a deadlock is possible for that order. (Assume that once a process acquires a resource, it does not release that resource until the end of that process.) a) 1, 2, 3 b) 1,3,2 c) 2, 1, 3 d) 2, 3, 1 e) 3, 1, 2 f) 3, 2, 1

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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Suppose a system has 5 processes, P = {P1, P2, P3, P4, P5}, and 4 resources, R = {R1, R2, R3, R4}, where there are 2 instances of R1, 1 instance of R2, 3 instances of R3, and 3 instances of R4. The current state of the system is defined by the following requests and assignments: P1 is requesting an instance of R3 and has been assigned an instance of R2; P2 is requesting an instance of R1 and has been assigned an instance of R3; P3 is requesting an instance of R4 and has been assigned an instance of R1 and an instance of R3; P4 is requesting an instance of R3; P5 is requesting an instance of R2 and has been assigned an instance of R4. Is there deadlock in this system? (Explicitly state yes, there’s deadlock or no, there isn’t.) If applicable, draw a wait-for graph or resource-allocation graph, and use the appropriate graph to justify your answer. If you conclude there is no deadlock, your justification should contain a sequence of execution for the processes which shows that…
b.Start from the resource allocation state in Q 13. If a request from a process P3 arrives for (1, 2, 3), can the request be immediately granted ? Why or why not ? c.Start from the resource allocation state in Q 13. Suppose that P4 asks for 2 instances of resource B. Can the system grant this if it wants to avoid deadlock ? Explain.
A system has three processes (P1,P2, P3) and three resources (R1,R2, R3). There is one instance of R1 and R2. There are three instances of R3. P1 holds an R1 and is requesting an R3. P2 holds an R3 and is requesting an R1. P3 holds two instances of R3 and an R2. Does a deadlock exist? Justify your answer.
Suppose processes P1-P4 with the given priorities and resource allocations. 1 is the highest priority and 4 is the lowest priority. Let us also assume that the "no preemption" condition is now relaxed by allowing preemption of resources by processes of higher priority. For example, P3 may preempt P2 or P4 if it needs a resource which they are holding. If P3 preempts one of these processes, say P4, then P4 release all the resources it is holding. Show one sequence of events in which resources are allocated to the 4 processes and the resulting preemptions, if any, until all new requests are serviced. Current allocations are shown below. Each resource has 4 instances. Try to minimize the preemptions as they are expensive. Process ID Process Priority Current allocation New request R1 R2 R1 R2 P1 1 2 1 2 1 P2 3 0 1 1 0 P3 2 1 1 0 1 P4 4 1 1 2 1
4. With a single resource, deadlock occurs a. if there are more than two processes competing for that resource b. if there are only two processes competing for that resource c. if there is a single process competing for that resource d. none of these
Hey, I have already received a good answer to this question but I am looking for greater detail to be provided. There are three processes P1, P2 and P3 are running in a system with 3 instances of a resource R1, 2 instances of a resource R2, and 2 instances of a resource R3. At a given time the allocation matrix is: A = [{1, 1, 1} { 0, 1, 0} { 1, 0, 0 }] Assume that the maximum matrix is M = [ {2,2,1} {1,1,1} {3,1,0}] While in this state, a new process P4 is created which requires at most 2 instances of R1 and one instance of R2. This process initially requests one instance of R1 to be allocated to it. Using the Banker’s algorithm, determine whether this request can be granted or must be refused.
Suppose there are three processes, P1, P2, and P3, and three files, FileA, FileB, and FileC. P1 has FileA and wants FileC. P2 has FileB and wants FileA. P3 has FileC and wants FileB. a) Draw a resource allocation graph for this situation. b) Does the graph represent a deadlock? Why or why not? Explain.
50. Match the following.i) Mutual exclusion a) A process may hold allocated resources while waiting assignment.ii) Hold and wait b) No resource can be forcibly removed from a process holding it.iii) No preemption c) Only one process may use a resource at a time. a. i-a, ii-b, iii-c b. i-a, ii-c, iii-b c. i-b, ii-c, iii-a d. i-c, ii-a, iii-b
Last solution had mistakes: For these questions, assume that memory partitions can be subdivided; multiple processes may fit in a partition if there is room. For example, if we had a 30-MB partition and a 20-MB process that fits in the partition, the partition’s new size is 10 MB after placing the process in it. If a second, 8-MB process arrives, we may place it in the partition, leaving 2 MB free in the partition. (The original memory partition then contains a 10-MB and an 8-MB process.) Consider a swapping system where memory has partitions of the following sizes: 180 MB, 100 MB, 40 MB, 200 MB, 300 MB, and 150 MB (in order). For first fit, how are processes of sizes 180 MB, 30 MB, 150 MB, 80 MB, 100 MB, and 70 MB placed (in order)? Indicate which requests (if any) cannot be satisfied. Repeat question (a) for best fit. Repeat question (a) for worst fit.
Consider 4 processes P0, P1, P2 and P3 that need to share 3 resource types A (10 instances), B(6 instances) and C (7 instances). The allocation of resources and the maximum need for 4processes as mentioned in the table.
Suppose at time T0, following is the snapshot of a system with 6 process (P0, P1, P2, P3, P4, P5) and 3 resources (A, B, C) having 8, 10 and 12 instances respectively.Allocation Max A B C A B CP0 2 3 1 4 4 4P1 1 0 3 3 3 3P2 0 2 2 1 2 3P3 1 2 1 2 2 2P4 0 2 1 0 3 5P5 2 0 2 2 1 2Now, if process P4 make a new request (0, 1, 2) for resources then state that whether this request can be granted or not using Banker’s Algorithm.
Suppose there are 8 processes in a system which are waiting to be assigned to the ready queue. The processes have the following properties. Process P1 has burst time 15, priority 6 Process P2 has burst time 12, priority 4 Process P3 has burst time 6, priority 12 Process P4 has burst time 5, priority 11 Process P5 has burst time 8, priority 9 Process P6 has burst time 9, priority 2 Process P7 has burst time 2, priority 20 Process P8 has burst time 17, priority 6 You have to use Multilevel Feedback Queue. It has three queues. The first queue takes processes with priority value from 1 to 5, the second queue takes processes with priority value of 6 to 10 and rest of the processes go to the third queue. First queue follows Round Robin Scheduling with time quantum= 4 Second queue follows Round Robin Scheduling with time quantum = 6 Third queue follows FCFC scheduling. Draw the gantt chart and calculate the average waiting time.