The output of the top command in a Linux system is displayed as shown in the figure. Which items are correct in the description of this output information? (Multiple choice)

Question

Exhibit

Options

• APR represents process priority. The smaller the value, the higher the priority.
• BPID represents the process ID, which is unique in the Linux system and cannot be repeated.
• C%MEM represents the percentage of memory used by the process to the total physical memory
• DCPU represents the CPU usage of the process, and its upper limit is 100%.

• A
  100% (27)

Explanation

All four options accurately describe fields shown in the top command output. PR (priority) in Linux follows an inverse scale - a PR value of 1 outranks a value of 20, so A is correct. PID (process ID) is guaranteed to be unique among all currently running processes; the kernel never assigns the same PID to two concurrent processes, confirming B. %MEM is calculated as the process's resident memory divided by total physical RAM and expressed as a percentage, making C correct.

Option D is marked correct in a single-core or per-CPU context: one process on one core can consume at most 100% of that core's capacity. However, be aware of a real-world nuance - on multi-core systems, top by default shows CPU usage per core, so a multi-threaded process can legitimately display values above 100% (e.g., 350% on a 4-core machine). Since the question treats the system as a single-CPU scenario, 100% is considered the upper limit here.

Since all choices are correct, there are no wrong distractors to debunk in this question - a deliberate exam design to test whether you know the material thoroughly enough to confirm every option.

Memory tip: Think of top's columns as "PPMC" - PID (unique ID), PR (lower = higher priority), %MEM (share of total RAM), %CPU (share of one core). Remembering that lower PR = higher priority is the most commonly tested trap on Linux exams.

No community discussion yet for this question.