In operating system storage architecture, what is defined as 'Double Buffering'? (Set 35)
Definition of Double Buffering: Using two memory buffers so one buffer is processed by CPU while the other receives I/O data.
What happens in Round Robin (RR) scheduling if the time quantum is extremely SMALL?
An extremely small time quantum causes frequent context switches. The CPU spends a major fraction of its time switching between processes rather than executing actual task instructions.
In a system with 32-bit virtual addresses and 8 KB page size, how many entries are present in a single-level page table?
$Page size = 8 KB = 2^13 bytes. Number of entries = 2^32 / 2^13 = 2^19 = 524,288 entries.$
Which of the following statements regarding I/O Transfer Mechanisms are CORRECT?
DMA transfers entire data blocks without per-byte CPU intervention.
Which one of the following CPU scheduling algorithms cannot be preemptive?
- SRTF is explicitly the preemptive version of Shortest-Job-First - it can preempt a running process whenever a newly arrived process has a shorter remaining time.
- Round Robin is inherently preemptive - it forcibly preempts a running process once its time quantum expires.
- Priority Scheduling can be implemented in either a preemptive form (a higher-priority arrival preempts the current process) or non-preemptive form - so it certainly can be preemptive.
- FCFS (First Come First Serve) is defined by running processes strictly to completion in arrival order - there is no mechanism within FCFS for a later-arriving process to interrupt/preempt the one currently executing. It is inherently non-preemptive by definition.
Answer: First Come First Serve (FCFS) Scheduling cannot be preemptive.