Practice Test Geeks(LCA) Certified Linux Administrator Practice Test
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Performance Monitoring & Tuning Flashcards

7 cards from real LCA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Performance Monitoring & Tuning flashcards as text

  1. Which command measures and displays network interface statistics including packets, errors, and drops in real time?

    Answer: Both ip -s link and netstat -i show interface statistics

    Both 'ip -s link' and 'netstat -i' display per-interface packet counters; ip -s link is the modern preferred tool.

  2. What does 'numactl --membind' do when running a process on a NUMA system?

    Answer: Restricts memory allocations to specified NUMA nodes, reducing cross-node memory latency

    numactl --membind forces memory allocations to the listed NUMA nodes, improving locality for memory-intensive workloads.

  3. Which tool can trace kernel function calls and measure their latency using eBPF without modifying the kernel?

    Answer: bpftrace

    bpftrace uses eBPF programs to instrument kernel and user-space functions dynamically without kernel modification.

  4. A server shows high CPU steal time (st) in top. What does this indicate?

    Answer: A hypervisor is consuming CPU cycles that the VM requested, indicating resource contention on the host

    CPU steal time appears in virtualized environments when the hypervisor is running other guests and cannot service this VM's requests.

  5. What does the 'tuned' daemon do in Linux performance management?

    Answer: Applies predefined and custom tuning profiles to kernel parameters, CPU governors, and disk settings automatically

    tuned dynamically switches between profiles (e.g., throughput-performance, latency-performance) to optimize the system for its workload.

  6. Which command shows how much memory is currently used by the kernel's slab allocator (dentries, inodes, etc.)?

    Answer: slabtop

    slabtop displays real-time kernel slab cache usage, showing which object types consume the most memory.

  7. What is the recommended way to permanently apply sysctl tuning parameters across reboots?

    Answer: Add the parameters to a file in /etc/sysctl.d/ and run sysctl --system

    Files in /etc/sysctl.d/ are loaded at boot by systemd-sysctl; 'sysctl --system' applies them immediately without rebooting.