I m posting on this forum because I m not able to find anything elsewhere and I m looking for this for a couple of days without success
I have Debian 4.19.98 with PREEMPT Kernel patch-4.19.98-rt40, I compiled my kernel with PREEMPT options (Real Time - Basic RT + Group scheduling RR/FIFO )
Following this I installed rt-test to check latency of my OS using mainly cyclictest and all was working fine.
As finally I want to use docker containers I installed Docker and I built an image to embed rt-tests on my container and check the latency within a container.
Since I have installed Docker on my machine and run my container I m no more able to run cyclictest on my host OS get an error:
debian Unable to change scheduling policy!
either run as root or join realtime group => I m logged as root on my SSH connection and even on the system itself I get this error message.
I start my container with such command: docker run -it --cpu-rt-runtime=950000 --ulimit rtprio=99 --cap-add=sys_nice rt-test:latest
I have tried to create a realtime group with following coommand & settings:
# cat <<EOF >/etc/security/limits.d/99-realtime.conf
@realtime - rtprio 99
@realtime - memlock unlimited
EOF
Now even if I reboot and no container is running with cpu/cgroup setting I m no more able to make cyclictest on my host
cyclictest in my container works sometime but sometime I do also get the error :
debian Unable to change scheduling policy!
either run as root or join realtime group
Is there any chance someone could help me to workaround this issue.
My goal 'ideally" & if possible would be to test at the same time my OS latency and container latency
Thanks by advance for your help
Jerome