Consider the below implementations of a semaphore's wait and signal operations:wait () {Disable interrupts;sem.value--;if (sem.value < 0) {save_state (current) ; // current processState[current] = Blocked; //A gets blockedEnqueue(current, sem.queue);current = select_from_ready_queue();State[current] = Running;restore_state (current); //B starts running}Enable interrupts;}signal(){Disable interrupts;sem.value++;if (sem.value <= 0){k = Dequeue(sem.queue);State[k] = Ready;Enqueue (k, ReadyQueue);}Enable interrupts;}%3|a) What are the critical sections inside the wait and signal operations which are protected bydisabling and enabling of interrupts?b) Give example of a specific execution scenario for the above code leading to inconsistency ifthe critical sections inside implementation of wait() and signal0 are not protected (bydisabling of interrupts).c) Suppose that process A calling semaphore wait() gets blocked and another process B isselected to run (refer to the above code). Since interrupts are enabled only at the completionof the wait operation, will B start executing with the interrupts disabled? Explain youranswer.

Solution: a) sem.value is the one which is protected by wait and signal, because in the critical…

Consider the below implementations of a semaphore's wait and signal operations: wait () { Disable interrupts; sem.value--; if (sem.value < 0) { save_state (current) ; // current process State[current] = Blocked; //A gets blocked Enqueue(current, sem.queue); current = select_from_ready_queue(); State[current] = Running; restore_state (current); //B starts running signal(){ Disable interrupts; sem.value++; if (sem.value <= 0){ k = Dequeue(sem.queue); State[k] = Ready; Enqueue (k, ReadyQueue); } Enable interrupts; }

Consider the below implementations of a semaphore's wait and signal operations: wait () { Disable interrupts; sem.value--; if (sem.value < 0) { save_state (current) ; // current process State[current] = Blocked; //A gets blocked Enqueue(current, sem.queue); current = select_from_ready_queue(); State[current] = Running; restore_state (current); //B starts running signal(){ Disable interrupts; sem.value++; if (sem.value <= 0){ k = Dequeue(sem.queue); State[k] = Ready; Enqueue (k, ReadyQueue); } Enable interrupts; }

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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