Lesson 1When to kill, restart, or throttle a process: safe kill practices, systemctl restart, and using cgroups and nice/reniceKnow when to end, restart, or slow a process and how to do it safely. Learn signal types, safe kill ways, systemctl restart actions, and how to use cgroups and nice or renice to limit effects.
Choosing SIGTERM, SIGKILL, and othersUsing kill and pkill with safeguardsRestarting services with systemctlThrottling CPU with nice and reniceLimiting resources using cgroupsDocumenting and automating remediesLesson 2Analysing swap usage and OOM events: dmesg, kernel OOM killer logs, and /var/log/kern.logLook into swap use and Out Of Memory events with free, dmesg, kernel OOM logs, and /var/log/kern.log. Learn to spot thrashing, adjust swappiness, and choose when to add RAM or change limits.
Checking swap usage with free and /procRecognizing swap thrashing symptomsReading dmesg for OOM killer entriesParsing /var/log/kern.log detailsTuning swappiness and vm overcommitDeciding when to add RAM or adjust limitsLesson 3Identifying hot processes: ps, ps aux --sort, pgrep, pidstat and mapping PIDs to servicesLearn to quickly find hot or naughty processes using ps, pgrep, pidstat, and sorting options. Map PIDs back to services, units, and containers to link resource use with what's causing it.
Sorting ps output by CPU and memoryUsing pgrep and pkill name filtersMonitoring per-process stats with pidstatMapping PIDs to systemd unitsRelating PIDs to containers or cgroupsTracking short-lived bursty processesLesson 4Identifying recurring resource spikes: inspecting cron, systemd timers, at jobs, and application schedulersExplore ways to spot repeating CPU, memory, and I/O spikes by matching metrics with scheduled tasks. Check cron, systemd timers, at jobs, and app schedulers to find and fix noisy or overlapping jobs.
Listing and reading user and system crontabsInspecting systemd timers and calendar unitsReviewing at jobs and one-off schedulesTracing app-level schedulers and workersCorrelating spikes with job execution timesRefining or staggering noisy recurring jobsLesson 5Memory troubleshooting: free, /proc/meminfo, smem, pmap and checking for memory leaksBuild skills to fix memory issues using free, /proc/meminfo, smem, and pmap. Learn to tell cache from real pressure, find per-process use, and spot patterns showing memory leaks or fragmentation.
Interpreting free and available memoryReading /proc/meminfo key fieldsUsing smem for per-process breakdownsInspecting process maps with pmapSpotting memory leak growth patternsDifferentiating cache from real pressureLesson 6Integrating with monitoring data (Prometheus, Grafana) and using historical metrics to determine trendsLearn to mix local fixing with Prometheus and Grafana data. Use past metrics, dashboards, and alerts to spot trends, regressions, and slow changes, and check the effect of performance fixes.
Reviewing key CPU and load dashboardsInspecting memory, cache, and swap panelsAnalysing disk and network latency graphsUsing PromQL to slice historical metricsCorrelating deploys with metric changesValidating fixes with before and after viewsLesson 7Load vs CPU saturation: uptime, load average interpretation and relation to CPU coresClear up what system load averages mean and how they link to CPU cores and run queues. Learn to tell healthy high load from CPU saturation, and match load with I/O wait, context switches, and latency.
Reading uptime and load averagesRelating load to CPU core countsSeparating runnable and blocked tasksIdentifying CPU-bound saturation casesRecognizing I/O wait driven loadUsing vmstat and mpstat to confirmLesson 8Collecting live system metrics: top, htop, vmstat, mpstat, iostat and how to interpret outputsLearn to gather and make sense of live Linux performance metrics using top, htop, vmstat, mpstat, and iostat. Understand CPU, memory, and I/O views, key fields, refresh times, and how to spot bottlenecks live.
Reading CPU usage in top and htopMonitoring memory and swap in topUsing vmstat for system-wide snapshotsAnalysing CPU stats with mpstatChecking disk I/O patterns with iostatChoosing sampling intervals and filtersLesson 9Using perf, strace, and ltrace for deep process analysis and when to use eachKnow when and how to use perf, strace, and ltrace for deep process checks. Learn to profile CPU hot spots, trace system calls, check library calls, and keep overhead low while getting useful diagnostics.
Profiling CPU hotspots with perf recordViewing perf reports and call graphsTracing syscalls with strace safelyFiltering noisy strace outputInspecting library calls using ltraceChoosing the right tool for each symptomLesson 10Using lightweight profiling and tracing tools (py-spy, gdb, flamegraphs) for Python appsFocus on light profiling and tracing for Python apps using py-spy, gdb, and flamegraphs. Capture stack samples in production, find hot code paths, and read flamegraphs without stopping services.
Sampling Python stacks with py-spyGenerating and reading flamegraphsAttaching gdb safely to live PythonHandling stripped or optimized buildsProfiling async and multithreaded codeReducing profiler overhead in production
