Train your team

KRN-231 · Linux Kernel Core

RCU in Depth

Read-copy-update from first principles: grace periods, publish-subscribe, and why RCU is everywhere in the kernel.

Advanced 3 days in person6 half-days online Max 14 in person

Who this course is for

Kernel developers maintaining read-mostly concurrent data structures who need RCU used correctly — reasoned from the contract, not cargo-culted from an example.

Prerequisites

KRN-230 or solid kernel locking backgroundSolid CModule development experience

Course outline

Day 1 — The RCU contract

  • What RCU guarantees and what it does not
  • Read-side critical sections and their rules
  • Grace periods and quiescent states, conceptually
  • Why RCU is everywhere in the kernel
  • The cost model: when RCU wins and when it loses

Day 2 — Using it correctly

  • rcu_read_lock/rcu_read_unlock and nesting
  • rcu_dereference, rcu_assign_pointer and why the accessors exist
  • Publish-subscribe for adding and removing data
  • List RCU primitives: list_for_each_entry_rcu, list_add_rcu, list_del_rcu
  • call_rcu and kfree_rcu: callback processing and its cost

Day 3 — Variants and debugging

  • Preemptible RCU and what it changed
  • SRCU for sleeping readers and its trade-offs
  • RCU in the PREEMPT_RT kernel
  • Debugging RCU stalls and CPU stall warnings
  • Capstone workshop

Hands-on labs

Labs follow the academy model — 35% principles, 20% guided investigation, 45% engineering studio. Every claim you make in a lab is backed by a trace, a counter or a measurement you captured yourself. How we teach

  1. Lab: protect a shared list first with a rwlock, then with RCU, and compare read-side latency under contention
  2. Lab: publish and remove elements with the correct accessors and verify readers never observe torn data
  3. Lab: trigger an RCU CPU stall warning deliberately and decode the report
  4. Lab: convert a sleeping-reader path to SRCU and measure the trade-off
  5. Lab: stress an RCU data structure with concurrent readers and writers and prove grace-period correctness

Capstone project

Implement and defend an RCU-protected lookup structure in a module: correct accessor discipline throughout, a publish/remove path safe against concurrent readers, stall-free behaviour under a torture run, and a written explanation of where each guarantee comes from — the same argument you would make in a patch cover letter.

What you leave with

  • The RCU contract stated precisely, with its limits
  • Accessor discipline: rcu_dereference, rcu_assign_pointer, list primitives
  • Selection criteria across RCU, SRCU and RT variants
  • RCU stall diagnosis from the actual warnings

How it runs

Every course follows the same model: 35% principles, 20% guided investigation, 45% engineering studio. You leave with working code, raw measurements and an evidence-based report — not a certificate of attendance. Read the methodology or see a full sample lesson.

Material is adapted to your kernel version, hardware and workload before a private delivery. For public cohorts, the environment is provided and configured.

Questions

Who is this course for?

Kernel developers maintaining read-mostly concurrent data structures who need RCU used correctly — reasoned from the contract, not cargo-culted from an example. It sits at advanced level within the Linux Kernel Core track.

What do I need to know already?

Specific prerequisites for this course: KRN-230 or solid kernel locking background; Solid C; Module development experience. We confirm levels before the cohort starts and adapt if a group is stronger or weaker than expected.

Can this run privately for my team?

Yes. Any course runs on-site at your offices anywhere, or live online for a distributed team, with labs adapted to your hardware and codebase.

What is the difference between in-person and online?

In person is 3 full days with hardware on your desk, capped at 14. Online is 6 half-day sessions across about two weeks so you can keep working, capped at 20, with remote lab access.

Do you invoice companies?

Yes. Purchase orders are accepted and invoicing is available in USD, EUR, GBP, SAR and CAD.

Upcoming dates

DatesWhereSeatsEarly birdRegular
8 Nov – 10 Nov 20263 full days RiyadhIn person · KAFD Conference Centre 7 of 14 SAR 8,100until 9 OctSAR 9,000
8 Nov – 10 Nov 20263 full days Kuwait CityIn person · Al Hamra Tower 12 of 14 KWD 670until 9 OctKWD 740
15 Nov – 17 Nov 20263 full days MuscatIn person · Knowledge Oasis Muscat 7 of 14 OMR 830until 16 OctOMR 920
22 Nov – 29 Nov 20266 half-days Gulf bandLive online · 09:00–13:00 GMT+3 13 of 20 US$1,580until 23 OctUS$1,750
23 Nov – 25 Nov 20263 full days OttawaIn person · Kanata North Tech Park 12 of 14 CAD 2,930until 24 OctCAD 3,260
23 Nov – 25 Nov 20263 full days TorontoIn person · MaRS Discovery District 7 of 14 CAD 2,930until 24 OctCAD 3,260
23 Nov – 30 Nov 20266 half-days Europe bandLive online · 09:00–13:00 CET 18 of 20 US$1,580until 24 OctUS$1,750
30 Nov – 2 Dec 20263 full days LondonIn person · Shoreditch Works 12 of 14 GBP 1,680until 31 OctGBP 1,870
30 Nov – 7 Dec 20266 half-days Americas bandLive online · 13:00–17:00 ET 7 of 20 US$1,580until 31 OctUS$1,750
7 Dec – 9 Dec 20263 full days BerlinIn person · Factory Görlitzer Park 7 of 14 EUR 1,990until 7 NovEUR 2,210

Dates shown for the next few months. If nothing fits, tell us where and when — cohorts are added on demand, and private delivery can be scheduled any week.

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