rcub task affinity allows isolated cpus
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
StarlingX |
Fix Released
|
Low
|
Jim Somerville |
Bug Description
Brief Description
-----------------
The rcub task has affinity which allows it onto isolated cpus.
There is an upstream linux kernel commit which fixes this by removing nohz_full cpus from the task
affinity. This will work for us since isolated cpus are also marked as nohz_full.
Severity
--------
Minor, but the rcub task can steal precious cpu time away from kworker tasks on isolated cpus.
Steps to Reproduce
------------------
Boot an rt (lowlat) kernel, check the affinity of the rcub task(s). eg:
ps -efww | grep rcub
taskset -p 14 (if the above showed task 14 is rcub)
Expected Behavior
------------------
The affinity of rcub does not include nohz_full cpus
Actual Behavior
----------------
The affinity of rcub includes all cpus.
Reproducibility
---------------
100%
System Configuration
-------
Anything lowlat
Branch/Pull Time/Commit
-------
N/A
Last Pass
---------
This problem has been there since day one AFAICT
Timestamp/Logs
--------------
Don't need
Test Activity
-------------
Doesn't matter
Workaround
----------
Not required, but one can always manually change a task's affinity with taskset command.
Changed in starlingx: | |
assignee: | nobody → Jim Somerville (jsomervi) |
Changed in starlingx: | |
importance: | Undecided → Low |
tags: | added: stx.8.0 stx.distro.other |
Fix proposed to branch: master /review. opendev. org/c/starlingx /kernel/ +/860750
Review: https:/