Solution

The correct answer is option 1

Key Points

​Understanding Spinlocks (Busy-Waiting)
A spinlock is a type of lock where a process, instead of going to sleep when it finds a lock is busy, stays "awake" on the CPU and repeatedly checks the lock's status in a loop.

Analysis of the Statements
A. The name refers to busy waiting semaphores.
Verdict: Correct.

Reason: Because the process "spins" in a loop using CPU cycles while waiting, it is the definition of busy waiting.

B. They are not useful when the locks are to be held for a short duration of time.
Verdict: Incorrect.

Reason: Spinlocks are actually most useful for short durations. Putting a process to sleep and waking it up (context switching) is an expensive operation. If the lock will be released very quickly, it is faster to just spin for a few nanoseconds than to perform a full context switch.

C. It may require multiple context switches when a process waits on a lock.
Verdict: Incorrect.

Reason: This is the primary advantage of a spinlock: it requires zero context switches. The process never leaves the CPU, so no state saving or loading is required.

D. They are often employed on Uniprocessor systems.
Verdict: Incorrect.

Reason: Spinlocks are generally useless on uniprocessor (single-core) systems. If Process A is spinning on the only CPU waiting for a lock, Process B (which holds the lock) can never run to release it. On a uniprocessor, the spinning process would just waste its entire time slice until the OS forces a context switch anyway. They are designed for Multiprocessor environments where one core can spin while another core completes the task.