[Ksummit-discuss] [TECH TOPIC] Mainlining PREEMPT_RT

Linus Walleij linus.walleij at linaro.org
Wed Oct 14 07:35:08 UTC 2015


On Tue, Oct 13, 2015 at 6:42 PM, Steven Rostedt <rostedt at goodmis.org> wrote:

> The various topics would include:
>
>  CPU hotplug
>  preempt_disable and local_irq_disable annotations
>  new timer_wheel implementation
>  simple waitqueues
>  trylock boosting

- Decide on a case-per-case basis whether to make all irqchips threaded.

We recently ran into this in the GPIO subsystem as Grygorii Strashko
is working on RT on the ARM OMAP. So I drafted a checklist:
http://marc.info/?l=linux-gpio&m=144382150627266&w=2

Feedback welcome. I don't know if I even got the details right in that
checklist. There are a few irqchips around:

$ git grep 'struct irq_chip ' arch/ drivers/ | wc -l
721

If this isn't done I guess that for example a sudden IRQ on a GPIO
pin can delay a deadline. Not good.

Yours,
Linus Walleij


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