EX442 Sample Questions & Answers
Draws on three tied leaders: analyzing system behavior with Performance Co-Pilot, profiling applications with tools like Valgrind, and tuning systems through cgroups and tuned profiles, plus kernel parameters, memory page sizing, disk tuning, and network buffers.
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- Question 1Intermediate
Use Utilities to Analyze System Behavior · Performance Co-Pilot (PCP)
A system administrator needs to analyze historical disk write throughput between 10:00 AM and 11:00 AM from a PCP archive located at
/var/log/pcp/pmlogger/myserver/20230915. Which command correctly queries this specific time window?Show answer & explanation
Correct answer: C
The
pmvalcommand is used to display performance metric values. The-aflag specifies the archive source. The-S(start) and-T(terminate) flags specify the time window for the analysis.disk.all.writeis the metric for total disk write throughput. - Question 2Intermediate
Use Utilities to Analyze System Behavior · System performance monitoring utilities
You are troubleshooting a report of slow network performance that occurred yesterday. You verify that the
sysstatservice is enabled and active. Which command would you use to review the network statistics for theeth0interface from the previous day's standard daily data file?Show answer & explanation
Correct answer: A
sar -n DEVdisplays network statistics for devices. The-fflag is used to specify a historical data file. Standard sysstat daily files are stored in/var/log/sa/with the formatsaDD, where DD is the day of the month. - Question 3Advanced
Use Utilities to Analyze System Behavior · System performance monitoring utilities
A multi-threaded application running on a 32-core server is performing poorly.
topshows total CPU usage around 3%, but the application is sluggish. You runmpstat -P ALL 1and see that CPU 0 is at 100%%softusage while all other CPUs are idle. What is the most likely cause of this performance issue?Show answer & explanation
Correct answer: B
High
%soft(software interrupt) usage on a single core typically indicates that the core is overwhelmed processing SoftIRQs, often from network traffic. Ifirqbalanceis not running or configured correctly, or if Receive Packet Steering (RPS) is not configured, all network interrupts may hit a single CPU, creating a bottleneck even if total system CPU capacity is ample. - Question 4Beginner
Use Utilities to Analyze System Behavior · Hardware profiling utilities
You suspect that a performance degradation is caused by a mismatch in memory module speeds on a physical server. Which command would provide detailed information about the installed RAM modules, including their configured speed and manufacturer, to verify this hypothesis?
Show answer & explanation
Correct answer: B
dmidecodedumps the system's DMI (Desktop Management Interface) table contents. Using-t memory(or type 17) filters the output to show detailed physical memory information, including speed, type (DDR4/DDR5), manufacturer, and part number for each slot. - Question 5Beginner
Use Utilities to Analyze System Behavior · Hardware profiling utilities
A Java application crashes randomly. You suspect the Linux kernel is terminating the process due to memory exhaustion. Which command would most effectively confirm if the OOM (Out of Memory) killer was triggered for this process?
Show answer & explanation
Correct answer: B
The kernel logs OOM killer activity to the ring buffer. Using
dmesgfiltered for "killed process" or "Out of memory" will show if and when the kernel terminated a process to reclaim memory. - Question 6Advanced
Use Utilities to Analyze System Behavior · Performance Co-Pilot (PCP)
A high-frequency trading firm is designing a monitoring strategy for their RHEL 8 clusters. They require:
- Sub-second granularity for real-time analysis.
- Low overhead on the monitored systems.
- Historical data retention for 30 days.
- Centralized analysis capability.
Which toolset combination best meets these requirements?
Show answer & explanation
Correct answer: C
PCP is designed exactly for this scenario. It supports high-resolution (sub-second) metrics, has a distributed architecture (PMDAs on nodes, pmlogger for archiving), and is efficient.
sysstat(sar) typically runs at 1-10 minute intervals by default and is less suited for sub-second real-time aggregation across a cluster.graph LR Node1[Trading Node 1 pmcd] -->|metrics| Central[Central Monitor pmlogger] Node2[Trading Node 2 pmcd] -->|metrics| Central Node3[Trading Node 3 pmcd] -->|metrics| Central Central -->|archives| Analysis[Analysis Tool pmchart/Grafana]
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