Process Practice Questions

Interrupts are hardware signals that force the CPU to suspend the current task to handle external events. Device I/O controllers send signals to the CPU for servicing, power failures trigger Non-Maskable Interrupts (NMIs) to save state, and system timers issue periodic interrupts to enforce preemptive scheduling. In contrast, the scheduler is a kernel function invoked after an interrupt or system call has already occurred to determine the next process to execute. Therefore, the scheduler is not an interrupt source, but rather a mechanism that manages process transitions.

Swap space is a virtual memory technique used by operating systems to extend the capacity of physical $RAM$. When physical memory is exhausted, the operating system offloads inactive data pages to a dedicated section on a non-volatile storage medium, commonly referred to as the $Disk$ ($HDD$ or $SSD$). Because swap space requires persistence and large capacity, it is not implemented in volatile $RAM$, read-only $ROM$, or the tiny, high-speed on-chip cache. Thus, it physically resides on the $Disk$.

A context switch requires saving the state of process $A$ (registers) and loading the state of process $B$. To maintain memory isolation, the operating system updates the active page table (changing address translation tables) and invalidates or flushes the Translation Look-aside Buffer ($TLB$) entries to prevent mapping errors. Conversely, swapping the entire memory image of a process to the disk is a heavy I/O operation performed by the medium-term scheduler to manage physical memory, not a standard step executed every time the CPU switches tasks. Consequently, option C is not a typical component of a context switch.

The process state transition diagram includes a critical transition arrow from the $RUNNING$ state back to the $READY$ state. This specific transition indicates that a process is forcibly moved from the CPU back to the ready queue before its execution is complete, typically due to time-slice expiration or the arrival of a higher-priority task. In a non-preemptive scheduler, a process would only leave the $RUNNING$ state by voluntarily terminating or blocking for I/O. Therefore, the existence of the $RUNNING \rightarrow READY$ transition is the defining feature of a preemptive scheduler.

Compiling is not a process state.

fork() executes for i = 0,2,4,6,8, i.e. 5 times. Each such iteration doubles the current number of processes. Starting with 1 process gives 2^5 = 32 total processes, so child processes = 31.