Working-Set Model of Process Memory Behavior According to the working-set theory in operating systems, what does a process’s working set represent?

Introduction / Context:
The working-set model explains locality of reference in process memory usage and guides policies for page allocation and load control to minimize thrashing.

Given Data / Assumptions:

• Virtual memory with paging is in use.
• A time window (Delta) defines “recently used”.
• Locality implies clustered page references.

Concept / Approach:
The working set W(t, Delta) is the set of distinct pages referenced by a process during the interval of length Delta ending at time t. Ensuring enough frames to hold the working set reduces page faults and prevents thrashing.

Step-by-Step Solution:
Define Delta: a tunable window representing recent activity.Track page references within this window.Compute W as the unique set of pages touched in the window.Allocate frames ≥ |W| to meet demand and maintain performance.

Verification / Alternative check:
Empirical observations of program phases show stable working sets during phases and changes at phase boundaries, aligning with locality principles (temporal and spatial).

Why Other Options Are Wrong:
Option B: Disk scheduling concerns I/O queue order, not working-set content.Option C: Coalescing free holes is a heap/allocator concern, not paging.Option D: CPU scheduling is orthogonal to working-set memory behavior.Option E: Not applicable because Option A is correct.

Common Pitfalls:

• Confusing working set with resident set; working set is a target size, resident set is actual frames held.
• Choosing Delta too small or too large, leading to under- or over-provisioning.

Final Answer:
The collection of pages the process actively accesses over a recent window of time.