20. Hardware Assisted Synchronization

Question 1

Atomicity

Answer 1

• If two or more simple operations are part of the same atomic block, the hardware will process those operations in one shot

Question 2

Spinlock

Answer 2

• A type of synchronization where one process will spin (loop) until it is able to acquire the lock

Question 3

sem.count

Answer 3

• The number of processes that can concurrently utilize the shared resource
• Decremented when a new process requests access

Question 4

sem.queue

Answer 4

• Contains references to the tasks blocked on the resource

Question 5

sem.wait

Answer 5

• Used by the process to check if it can access the resource (decrements sem.count by 1)
• The task is inserted into the waiting queue if sem.count <= 0

Question 6

sem.signal

Answer 6

• Used by the process to indicate that it is done using the shared resource (increments sem.count by 1)

Question 7

Uses of Semaphores

Answer 7

• Mutual exclusion: initialize sem.count = 1
• Controlled MPL: initialize sem.count = K
• Relative ordering of code: initialize sem.count to 0 and have the latter process wait for the former process to signal