Operating System

Question

Answer 1

Answer : Semaphore

Shared memory is faster because the data is not copied from one address space to another, memory allocation is done only once, and synchronization is up to the processes sharing the memory. mostly, shared memory just give more control but if you use your shared memory like a pipe, it probably won't make much difference depending on your kernel implementation.

Reference : https://stereochro.me/assets/uploads/notes/dcom3/shmem.pdf

Read the section of shared memory and Semaphore

Answer 2

Answer is D).

Shared memory is faster than message passing IPC mechanisms .

Pipes, mailboxes all are used for message passing .

But semaphores are used in shared memory to synchronise the common shared area (critical section) and provide mutual exclusion.