CONFIG_NO_HZ_FULL configuration option

[LaurentBonnaud]

Hi,
I am trying to debug the following error messages:

# dmesg | grep NOHZ
[   27.342486] NOHZ tick-stop error: local softirq work is pending, handler #08!!!
[  385.030016] NOHZ tick-stop error: local softirq work is pending, handler #08!!!
[  570.593266] NOHZ tick-stop error: local softirq work is pending, handler #08!!!
[ 1847.759387] NOHZ tick-stop error: local softirq work is pending, handler #08!!!
[ 2238.979446] NOHZ tick-stop error: local softirq work is pending, handler #08!!!
[ 2274.558460] NOHZ tick-stop error: local softirq work is pending, handler #08!!!
[ 2307.472767] NOHZ tick-stop error: local softirq work is pending, handler #08!!!
[ 2324.570147] NOHZ tick-stop error: local softirq work is pending, handler #08!!!
[ 2339.015084] NOHZ tick-stop error: local softirq work is pending, handler #08!!!
[ 2349.607567] NOHZ tick-stop error: local softirq work is pending, handler #08!!!

and noticed that Zabbly kernels do not have the same config as Ubuntu kernels:

$ grep NO_HZ_FULL /boot/config-*
/boot/config-6.11.0-13-generic:CONFIG_NO_HZ_FULL=y
/boot/config-6.12.3-061203-generic:CONFIG_NO_HZ_FULL=y
/boot/config-6.12.9-zabbly+:# CONFIG_NO_HZ_FULL is not set

Is there a good reason to differ from Ubuntu kernels?

[stgraber]

No particular reason. I believe the last full config sync with Ubuntu was back in 6.9 or 6.10, so this is likely something that they have changed since. In general the behavior of the Zabbly kernel for newly introduced feature is to build as module if possible and if not, default to the recommended default value from the kernel config (often disabled for new features).