Throughput and scheduling — multiprogramming effect: Which statement best describes a typical advantage of multiprogramming systems compared to single-program systems?

Difficulty: Easy

Correct Answer: execute more jobs in the same time period

Explanation:


Introduction / Context:
Multiprogramming allows multiple jobs to reside in memory at once, so the CPU can switch to another job when one blocks for I O. This improves overall throughput and resource utilization compared to running a single job at a time.



Given Data / Assumptions:

  • Jobs may be CPU bound or I O bound.
  • Context switching overhead exists but is outweighed by reduced idle time.
  • We compare aggregate performance (throughput), not individual job runtime.


Concept / Approach:

By overlapping CPU time of one job with I O wait of another, multiprogramming decreases total idle time. This means more jobs complete within a fixed interval. Individual jobs may not finish faster, but the system completes more work overall, increasing throughput.



Step-by-Step Solution:

Define the goal: improve system utilization and throughput.Recognize that multiprogramming keeps the CPU busy while other jobs wait on I O.Conclude that more jobs finish per unit time.Select the option that states “execute more jobs in the same time period.”


Verification / Alternative check:

Queueing theory and empirical OS measurements show throughput improvements under multiprogramming, especially with mixed workloads.



Why Other Options Are Wrong:

  • Easier to develop: false; multiprogramming is more complex.
  • Execute each job faster: often not true; context switching can slow individual jobs slightly.
  • Only on mainframes: false; all modern systems use multiprogramming.
  • None of the above: incorrect because one option is correct.


Common Pitfalls:

Confusing response time improvements for short jobs with universal speedups; throughput gains do not guarantee faster completion for every job.


Final Answer:

execute more jobs in the same time period

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