Are you sure you have your kernel patched with -rt patches?
CONFIG_PREEMPT_RT_FULL=y was still needed in 4.19, AFAICT.

Please, could you refer to reply above (practical exercises using
lava_server_vm VM) to Ben and Daniel? You can also check and verify
it...

Maybe, after all, I am doing something very wrong. But I do not
see/not aware what?!

Zoran
_______


On Fri, Jul 19, 2019 at 3:59 PM Pavel Machek <pavel@ucw.cz> wrote:

Hi!

I started my own investigation about RT kernels, namely 4.19. I
proceed very carefully over the kernel config parameters... BUt the
last one I inspected today got me nowhere!?

Seems, that the following config parameters are obsolete in 4.19:
CONFIG_PREEMPT_RT_FULL

This one (CONFIG_PREEMPT_RT_FULL) is still present in 4.4 .

[vuser@fedora30-ssd kernel-config]$ cat CONFIG-4.4.120-rt-bbb | grep PREEMPT
CONFIG_PREEMPT_RCU=y
CONFIG_PREEMPT=y
CONFIG_PREEMPT_RT_BASE=y
CONFIG_HAVE_PREEMPT_LAZY=y
CONFIG_PREEMPT_LAZY=y
# CONFIG_PREEMPT_NONE is not set
# CONFIG_PREEMPT_VOLUNTARY is not set
# CONFIG_PREEMPT__LL is not set
# CONFIG_PREEMPT_RTB is not set
CONFIG_PREEMPT_RT_FULL=y <<======= Obsolete in 4.19 ?
CONFIG_PREEMPT_COUNT=y
CONFIG_DEBUG_PREEMPT=y
[vuser@fedora30-ssd kernel-config]$

What I should do to maintain RT-kernel-4.19? It is obvious, I must/need to set:
CONFIG_PREEMPT=y

Are you sure you have your kernel patched with -rt patches?
CONFIG_PREEMPT_RT_FULL=y was still needed in 4.19, AFAICT.

Note that not every piece of hardware has suitable characteristics for
realtime / low latencies.

Best regards,
Pavel

--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html