GATE | GATE CS 1999 | Question 68
Last Updated :
10 Oct, 2017
[5 Marks question]
a. A certain processor provides a ‘test and set’ instruction that is used as follows:
TEST register, flag
This instruction atomically copies flag to register and sets flag to 1. Give pseudo-code for implementing the entry and exit code to a critical region using this instruction.
b. Consider the following solution to the producer-consumer problem using a buffer of size 1. Assume that the initial value of count is 0. Also assume that the testing of count and assignment to count are atomic operations.
Producer:
Repeat
Produce an item;
if count = 1 then sleep;
place item in buffer.
count = 1;
Wakeup(Consumer);
Forever
Consumer:
Repeat
if count = 0 then sleep;
Remove item from buffer;
count = 0;
Wakeup(Producer);
Consume item;
Forever;
Show that in this solution it is possible that both the processes are sleeping at the same time.
Answer:
Explanation:
Quiz of this Question
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