GATE CS 2015 Set 3 Q.11 (CS Q.1): Processes, Threads and System Calls

The maximum number of processes that can be in Ready state for a computer system with $n$ CPUs is

$n$

$n^2$

$2^n$

Independent of $n$

Official answer and solution

Solution

Differentiate between the Ready state and the Running state in the operating system process lifecycle.

In an operating system:

The Running state contains processes currently being executed by processors. For a system with $n$ CPUs, at most $n$ processes can be in the Running state at any given instant.
The Ready state contains all processes that are ready to run and waiting in main memory (in the ready queue) for CPU time to be scheduled to them.
The size of the ready queue depends on system resources (main memory capacity and maximum allowable entries in the process table), not on the number of physical CPU cores $n$ present in the system.

Therefore, the maximum number of processes that can reside in the Ready state is independent of $n$ (Option D).

Final answer

Common trap

Confusing the Ready state with the Running state, which is strictly limited to $n$ processes for $n$ CPUs.

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