https://wiki.linuxfoundation.org/realtime/rtl/start

https://wiki.linuxfoundation.org/realtime/rtl/all_topics

https://www.embedded-software-engineering.de/entwicklung-einer-linux-realtime-applikation-a-b862ea485a877e6a7e2f25edd98f5ef7/

====== Learning ======

https://realtime-linux.org/a-checklist-for-real-time-applications-in-linux/

https://bootlin.com/training/preempt-rt/


====== Core partitioning ======

User-space partitioning, core isolation, NO_HZ_FULL

Dual-OS partitioning, using a POSIX RTOS in some cores, over a hypervisor

https://yosh.ke.mu/raspberry_pi_isolating_cores_in_linux_kernel


====== Multitasking ======
In user space:
  * Process (fork)
  * Thread (pthread_create)

In kernel:
  * Kernel thread (kthreadd)

====== Scheduler ======
sched_class
stop > dl > rt > cfs > idle
(e.g. rt threads will run with higher priority than cfs threads)
(stop and idle scheduling class are not accessible for user space applications)

rt includes SCHED_FIFO and SCHED_RR policies.

dl includes SCHED_DEADLINE policy (augmented EDF).


====== Utilities ======
  * chrt
  * taskset

==== Linux specific APIs ====
  * sched_setattr
  * sched_setaffinity
  * CPU_SET
  * pthread_setaffinity_np

==== POSIX realtime APIs ====
  * sched_setscheduler
  * ...


==== Benchmarking ====

Latency measurement with **cyclictest** (results for SCHED_FIFO).

Sources of latency:
  * Kernel system call
  * ISR
  * Kernel locks
  * Priority inversions
  * Timers
  * Page faults

**Ftrace**

**Kernel Shark**

**LLTng**