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Red Hat Certified Specialist in Performance Tuning exam Free Sample Questions

Description

Covers Performance Co-Pilot and hardware profiling, kernel runtime parameters, process and Valgrind analysis, tuned profiles and cgroups, memory page size tuning, I/O scheduling, and network buffers.

12 free sample questions135 in the full practice test

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EX442 Sample Questions

  1. Question 1

    Intermediate

    Use Utilities to Analyze System Behavior · System performance monitoring utilities

    A financial institution is running a latency-sensitive trading application on Red Hat Enterprise Linux 8. The application performance degrades intermittently. You capture the following iostat output during a degradation event:

    avg-cpu: %user %nice %system %iowait %steal %idle
12.40 0.00 4.10 48.50 0.00 35.00

Device tps kB_read/s kB_wrtn/s kB_read kB_wrtn
nvme0n1 850.00 4500.0 125000.0 ... ...

    Based on these metrics, which subsystem is the primary bottleneck and what is the most appropriate next step to analyze the root cause?

    Answer and explanation

    Correct answer: C

    The iostat output shows a high %iowait (48.50%) and significant write throughput (125MB/s) relative to the read throughput, while the CPU idle time is 35%. This indicates the system is waiting on I/O completion rather than being CPU bound. The next logical step is to identify which process is generating this I/O using tools like iotop or pidstat -d. Checking CPU saturation would be incorrect as the CPU is largely idle waiting for I/O.

    graph TD A[Analyze iostat] --> B{High %iowait?} B -- Yes --> C{High Throughput?} B -- No --> D[Check CPU/Memory] C -- Yes --> E[Identify Process (iotop/pidstat)] C -- No --> F[Check Disk Health/Latency] E --> G[Tune Application/Filesystem]

  2. Question 2

    Advanced

    Use Utilities to Analyze System Behavior · System performance monitoring utilities

    You are analyzing a database server using vmstat 1 and observe the following output consistently:

    procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu-----
r b swpd free buff cache si so bi bo in cs us sy id wa st
15 0 0 250000 50000 800000 0 0 5 10 4000 8500 85 14 1 0 0

    The server has 8 vCPUs. Which conclusion is most accurate based on this data?

    Answer and explanation

    Correct answer: A

    The r column (runnable processes) is 15, which is nearly double the number of vCPUs (8). The us (user) + sy (system) CPU usage is 99%, and idle is 1%. This indicates clear CPU saturation. The run queue depth (r) exceeding the core count confirms that processes are waiting for CPU time. Swap (si/so) and I/O (bi/bo) are negligible.

  3. Question 3

    Beginner

    Use Utilities to Analyze System Behavior · Performance Co-Pilot (PCP)

    You need to configure Performance Co-Pilot (PCP) to archive performance metrics every 10 seconds for historical analysis on a critical production server. You have installed the pcp and pcp-zeroconf packages. Which service must be enabled and started to ensure metrics are being written to archive logs?

    Answer and explanation

    Correct answer: C

    pmlogger is the PCP service responsible for creating and writing archive logs. While pmcd (Performance Metrics Collector Daemon) is required to collect the metrics, pmlogger is the specific component that persists them to disk for historical analysis. pcp-zeroconf typically sets up a default configuration for this.

  4. Question 4

    Intermediate

    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?

    Answer and explanation

    Correct answer: C

    The pmval command is used to display performance metric values. The -a flag specifies the archive source. The -S (start) and -T (terminate) flags specify the time window for the analysis. disk.all.write is the metric for total disk write throughput.

  5. Question 5

    Intermediate

    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 sysstat service is enabled and active. Which command would you use to review the network statistics for the eth0 interface from the previous day's standard daily data file?

    Answer and explanation

    Correct answer: A

    sar -n DEV displays network statistics for devices. The -f flag is used to specify a historical data file. Standard sysstat daily files are stored in /var/log/sa/ with the format saDD, where DD is the day of the month.

  6. Question 6

    Advanced

    Use Utilities to Analyze System Behavior · System performance monitoring utilities

    A multi-threaded application running on a 32-core server is performing poorly. top shows total CPU usage around 3%, but the application is sluggish. You run mpstat -P ALL 1 and see that CPU 0 is at 100% %soft usage while all other CPUs are idle. What is the most likely cause of this performance issue?

    Answer and 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. If irqbalance is 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.

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