Topic is Operating Systems.

Some questions could have multiple correct answers.
Choose all correct answers.
a point for each correct answer selected.
a half-point off for each incorrect answer selected.

09 QUESTION 15 The Barbershop Problem in the text requires what? OA. FIFO order for waiting customers on the sofa. OB. FIFO order for waiting customers in the standing room. oc. producer/consumer synchronization on the payment process. OD. mutual exclusion on the cash register. Hint: the barbershop problem applies mutual exclusion to each of the 3 barber chairs; there are two levels of waiting areas: the sofa and the standing room; synchronization involves making sure that the two waiting areas are served in a FIFO order; a barber cannot accept payment until the customer pays: there is only one cash register. QUESTION 17 The sigsuspend(szeromask) system call is an example of OA. the use of signals. OB. busy waiting. OC. strong semaphores. OD. message passing. Hint: sigsuspend sleeps until it gets a signal - there is no busy waiting. QUESTION 18 In message passing, sending a message to a shared temporary data structure (1 answer) OA. is called direct addressing. OB. is called indirect addressing. Oc. is called blocking. OD. is called a dead drop. Hint: also called a mailbox QUESTION 19 If you use message passing for synchronization, the sender can be (1 answer OA. either blocking or non-blocking. OB. blocking only. Oc. non-blocking only. Hint: depending on the situation you may want the sender to block until the receiver grabs the message or you may want the send to not block. QUESTION 20 Mutual exclusion on a single processor could be implemented (although not necessarily recommended that you do so) in hardware by (1 answer) OA. overlapping processes. OB. interleaving processes. oc. disabling interrupts. Hint: Overlapping is a term referring to multiple processes that are spread across multiple CPUs: disabling interrupts would prevent a critical section of code of one thread from being preempted by another thread that might be also executing the same critictal code - this is not a recommended way to do it for obvious reasons but it would work