COSC 3360/6310 - Operating Systems Spring 2022

Programming Assignment 2 - Deadlock Avoidance with EDF plus LJF-Tie-Breaker Scheduling and LLF plus SJF-Tie-Breaker Schedul- ing

integers and then by n * m integers. Next, the instructions for each of the n processes are given.

1000. /* nuber of resources */
14. /* umber of processes */

available[1] = number of instances of resource 1

:

available[m] = number of instances of resource m

max[1,1] = maximum demand for resource 1 by process 1

:

max[n,m] = maximum demand for resource m by process n

process_1:

deadline_1           /* an integer, must be >= computation time */ computation_time_1 /* an integer, equal to number of requests and releases */

:                  /* plus the parenthesized values in the calculate and      */

:                  /* use_resources instructions.      */

:

calculate(2);           /* calculate without using resources */ calculate(1);

request(0,1,0,...,2);   /* request vector, m integers */ use_resources(4);       /* use allocated resources */ calculate(3);

use_resources(6);       /* use allocated resources */

print_resources_used;   /* print process number and current master string */

:

release(0,1,0,...,1);   /* release vector, m integers */ calculate(3);

:

request(1,0,3,...,1);   /* request vector, m integers */ use_resources(5);

:

print_resources_used;   /* print process number and current master string */ end.

:

process_n:

deadline_n           /* an integer */

computation_time_n   /* an integer, equal to number of requests and releases */

:                  /* plus the parenthesized values in the calculate and      */

:                  /* use_resources instructions.      */

:

calculate(3);           /* calculate without using resources */

:

request(0,2,0,...,2);   /* request vector, m integers */ use_resources(2);       /* use allocated resources */ use_resources(5);

print_resources_used;   /* print process number and current master string */ use_resources(3);

:

release(0,1,0,...,2);   /* release vector, m integers */ calculate(4);

calculate(5);

:

request(1,0,3,...,1);   /* request vector, m integers */ use_resources(8);

print_resources_used;   /* print process number and current master string */ calculate(3);

:

print_resources_used;   /* print process number and current master string */ end.

Each resource consists of an English word (a string of characters) indicating an entity, item, food type, etc., followed by a list of resource instances (brands, actual item, etc.) consisting of English words to be read from a second input file or from standard input (stdin). For example, there are 5 resources (types): hotel, fruit, car, tool, and vegetable, with 6, 8, 7, 5, and 8 instances, respectively. Note that the names of the instances of each resource (type) are different, but they are instances of the same resource (type). When a process requests x instances of a resource, any x instances of this resource are acceptable. To ensure that resource instances are allocated mutually exclusively (one instance can only be allocated to one process), you will need Unix/Linux semaphores. The input file for this example is:

R1: hotel: Hilton, Marriott, Omni, Intercontinental, Westin, Sheraton R2: fruit: orange, mango, pear, apple, lemon, banana, watermelon, guava R3: car: Ford, Mercedes, BMW, Chrysler, Volvo, Porshe, Ferrari

R4: tool: screwdriver, drill, wrench, plier, hammer

R5: vegetable: lettuce, celery, broccoli, tomato, spinach, carroa, potato, onion

The main process executes the Banker’s algorithm. The resource-requesting processes are re- quired to make requests by communicating with the deadlock-handling process with Unix/Linux