Lesson 1Memory analysis: free -m, /proc/meminfo, slabtop, smem—interpreting used vs available memory and swap behaviorHere you go check memory how it work using free, /proc/meminfo, slabtop, and smem. The part explain Linux caching, buffers, and reclaim, how to understand swap use, and how to spot memory leaks, fragmentation, and wrong limits.
Reading free -m and understanding cached memoryKey fields in /proc/meminfo for diagnosisUsing slabtop to inspect kernel slab usageUsing smem to attribute memory per processRecognizing swap thrashing and OOM risksLesson 2Network usage and bottlenecks: iftop, nload, ss, netstat, ip -s link, tc, tcpdump—identifying network saturation and problematic connectionsThis part cover checking network use and blocks using iftop, nload, ss, ip, tc, and tcpdump. You go learn to spot saturation, noisy neighbors, connection states, and packet problems that make apps slow.
Monitoring live bandwidth with iftop and nloadInspecting sockets and states with ssUsing ip -s link to view interface errorsBasics of tc for shaping and rate limitingTargeted packet capture with tcpdumpLesson 3Storage latency and deeper I/O: blktrace, bpftrace (basic scripts), fio for tests—how to measure and interpret latency and throughputThis part cover storage latency and deep I/O check using blktrace, basic bpftrace scripts, and fio tests. You go learn to measure latency and throughput, understand queue depth, and tell device limits from workload problems.
Understanding latency, IOPS, and throughputUsing blktrace to inspect block I/O patternsIntroductory bpftrace scripts for disk latencyDesigning fio workloads that mimic productionReading fio reports and spotting bottlenecksLesson 4Process investigation: ps, top/htop filters, pgrep, pidstat, nice/renice—how to find CPU- and memory-heavy processesYou go learn to check processes with ps, top or htop filters, pgrep, pidstat, and nice or renice. The part show how to find CPU and memory heavy tasks, track per process I/O, and adjust priorities to cut contention.
Listing and filtering processes with psUsing pgrep and pkill safely and preciselyUsing pidstat for per process CPU and I/OFiltering top and htop by user or resourceAdjusting priorities with nice and reniceLesson 5System resource overview: top, htop, vmstat, mpstat, dstat—what each shows and expected output patternsHere you go learn to read whole system resource snapshots using tools like top, htop, vmstat, mpstat, and dstat. The part focus on understanding CPU, memory, and load metrics, and knowing normal from bad usage patterns.
Key CPU, load, and memory fields in topUsing htop for interactive process analysisvmstat for run queue, swap, and I/O insightmpstat for per-CPU utilization and steal timedstat for combined multi-resource timelinesLesson 6Disk I/O and filesystem checks: iostat, iotop, sar -d, lsblk, df -h, du -sh, tune2fs, xfs_info—detecting I/O bottlenecks and low spaceThis part focus on disk I/O and filesystem health using iostat, iotop, sar -d, lsblk, df, du, tune2fs, and xfs_info. You go learn to spot saturation, queue buildup, filesystem errors, and low space that hurt performance.
Using iostat to spot busy and slow devicesUsing iotop to find I/O heavy processessar -d for historical disk utilization trendsChecking layout and types with lsblk and dfFinding space hogs with du and inode checksLesson 7System logs and journaling: journalctl (systemd), /var/log/messages, /var/log/syslog, auth logs—what to search for and whyThis part explain how to use systemd journalctl and old log files like /var/log/messages, /var/log/syslog, and auth logs. You go learn what patterns to search, how to filter noise, and how logs help find root causes.
journalctl basics and useful filtering optionsReading /var/log/messages and /var/log/syslogFinding errors, warnings, and rate-limited eventsAnalyzing authentication and sudo related logsCorrelating log timestamps with incidentsLesson 8Time-based and historical monitoring: sar, sysstat, collectl—collecting and reading historical metrics to correlate eventsYou go learn how to collect and understand past metrics using sar, sysstat, and collectl. The part explain how to set data collection, read time series reports, and match performance problems with config changes or deployments.
Enabling and configuring sysstat collectionUsing sar for CPU, memory, and I/O historyReading sar network and load average trendsUsing collectl for multi-resource timelinesCorrelating metrics with change windowsLesson 9Kernel and scheduler insights: dmesg, sysctl -a, /proc/sys/vm parameters—what kernel messages and tunables revealHere you go explore kernel and scheduler insights using dmesg, sysctl, and /proc/sys/vm parameters. The part explain how kernel messages, tunables, and scheduler behavior show hardware issues, wrong configs, and tuning options.
Reading dmesg for hardware and driver issuesListing and querying sysctl tunable valuesKey /proc/sys/vm parameters for memoryScheduler related kernel parameters overviewSafely persisting kernel tuning changesLesson 10Approach to root cause determination: step-by-step decision tree to classify issues as CPU, RAM, disk I/O, or networkThis part show a practical decision tree for root cause check. You go learn how to class incidents as CPU, memory, disk I/O, or network bound, which tools to run in each part, and how to refine ideas using evidence.
Initial triage and problem statementClassifying CPU versus I/O bound symptomsDistinguishing memory pressure from leaksIdentifying network versus local bottlenecksIterative hypothesis testing with metrics
