KRN-222 · Linux Kernel Core · Advanced
Memory Pressure, OOM & cgroup v2 — full syllabus
What happens when memory runs out: reclaim, swap, the OOM killer, and cgroup v2 limits that throttle silently.
Who this course is for
SREs, platform and kernel engineers on call for memory stalls and OOM kills who want to diagnose pressure and configure limits deliberately instead of restarting services and hoping.
Prerequisites
- KRN-220-level VM knowledge
- cgroup v2 basics
- Linux administration
Course outline
Day 1 — Reclaim
- Direct vs background reclaim and kswapd behaviour
- LRU lists and the active/inactive balance
- Refault detection and what refaults tell you
- Watermarks and allocation stalls
- The /proc/vmstat counters that actually matter
Day 2 — Swap and the OOM killer
- Swap behaviour and swappiness on current kernels
- The OOM killer: scoring, oom_score_adj and victim selection
- memory.oom.group and killing as a unit
- Reading OOM reports in dmesg line by line
- Proactive handling vs reactive cleanup
Day 3 — cgroup v2 limits and PSI
- memory.max vs memory.high and their different semantics
- memory.low protection and when it holds
- PSI: some vs full stall metrics and how to read them
- Diagnosing stalls that look like CPU problems but are memory
- Capstone workshop
Hands-on labs
- Lab: force direct reclaim and watch allocation stalls appear in vmstat and PSI
- Lab: tune the active/inactive balance under a refault-heavy workload and show refault counts changing
- Lab: trigger the OOM killer under cgroup limits, decode the dmesg report and redirect victim selection with oom_score_adj and memory.oom.group
- Lab: throttle a service with memory.high and observe the resulting PSI stall signatures
- Lab: build a PSI-based monitor for one service and catch a memory stall that CPU metrics missed
Capstone project
Given a service that intermittently stalls and occasionally dies, produce a root-cause report with prevention built in: PSI timelines proving memory stalls, reclaim and OOM events correlated from logs, cgroup v2 limits and protections configured with justification, and a monitoring specification that would have caught the problem hours earlier.
What you leave with
- Reclaim and kswapd behaviour you can read from vmstat
- OOM mechanics and control over victim selection
- memory.max/high/low configured deliberately, not by imitation
- PSI-based diagnosis of memory stalls masquerading as CPU problems
Upcoming dates
| Dates | Where | Seats | Early bird | Regular | |
|---|---|---|---|---|---|
| 22 Nov – 24 Nov 20263 full days | RiyadhIn person · KAFD Conference Centre | 7 of 14 | SAR 8,100until 23 Oct | ||
| 29 Nov – 1 Dec 20263 full days | Kuwait CityIn person · Al Hamra Tower | 12 of 14 | KWD 670until 30 Oct | ||
| 6 Dec – 8 Dec 20263 full days | MuscatIn person · Knowledge Oasis Muscat | 7 of 14 | OMR 830until 6 Nov | ||
| 6 Dec – 13 Dec 20266 half-days | Gulf bandLive online · 09:00–13:00 GMT+3 | 15 of 20 | US$1,580until 6 Nov | ||
| 7 Dec – 9 Dec 20263 full days | OttawaIn person · Kanata North Tech Park | 12 of 14 | CAD 2,930until 7 Nov | ||
| 14 Dec – 16 Dec 20263 full days | TorontoIn person · MaRS Discovery District | 7 of 14 | CAD 2,930until 14 Nov | ||
| 14 Dec – 21 Dec 20266 half-days | Europe bandLive online · 09:00–13:00 CET | 4 of 20 | US$1,580until 14 Nov | ||
| 14 Dec – 21 Dec 20266 half-days | Americas bandLive online · 13:00–17:00 ET | 9 of 20 | US$1,580until 14 Nov | ||
| 21 Dec – 23 Dec 20263 full days | LondonIn person · Shoreditch Works | 12 of 14 | GBP 1,680until 21 Nov | ||
| 21 Dec – 23 Dec 20263 full days | BerlinIn person · Factory Görlitzer Park | 7 of 14 | EUR 1,990until 21 Nov |
Book a seat, or bring this course to your team
Seats can be reserved online; private delivery runs on-site or live online, adapted to your stack.
Questions about fit or prerequisites? Email hello@kernelsystems.academy. To save this syllabus, print this page to PDF from your browser.