RFE: Introduce plugin for cores isolation

[yarda]

At the moment Tuned uses Tuna for cores isolation, but it's not flexible enough. It would be better to have this functionality in Tuned plugin (CPU plugin?, scheduler plugin?, or different plugin?). It would provide better performance and flexibility for e.g. process whitelisting.

[jeremyeder]

I used the scheduler plugin in a whitepaper to do core affinity for a netperf test. It needs more flexibility, and at least to me the syntax was a bit difficult. If you look at /etc/rtgroups syntax, I bet we need something similar.

Look at the syntax of this file. It lets you create a comprehensive map of both user and kernel threads.

This tuning was laid down by the rtctl system service.

kthreads:*:1:*:\[.*\]$
watchdog:f:99:*:\[watchdog.*\]
migration:f:99:*:\[migration\/.*\]
softirq:f:70:*:\[.*(softirq|sirq).*\]
softirq-net-tx:f:75:*:\[(softirq|sirq)-net-tx.*\]
softirq-net-rx:f:75:*:\[(softirq|sirq)-net-rx.*\]
softirq-sched:f:1:*:\[(softirq|sirq)-sched\/.*\]
rpciod:f:65:*:\[rpciod.*\]
lockd:f:65:*:\[lockd.*\]
nfsd:f:65:*:\[nfsd.*\]
hardirq:f:85:*:\[(irq|IRQ)[\-_/].*\]

https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_MRG/1.3/html/Realtime_Tuning_Guide/chap-Realtime_Tuning_Guide-Realtime_Specific_Tuning.html#sect-Realtime_Tuning_Guide-Realtime_Specific_Tuning-Setting_Scheduler_Priorities

[yarda]

IIRC we have created scheduler plugin syntax according to /etc/rtgroups. I.e. the only difference should be that the group name starts with 'group.'

[jeremyeder]

I checked our IRC logs, and you're right, we did. Your memory is better than mine :+1:

[olysonek]

Am I missing something, or do the isolated_cores, ps_blacklist and ps_whitelist options of the scheduler plugin provide the required functionality? These have been introduced in commit ac78f90c773cc97573844f521c2f67291f15d354.