Hi Christian, I see a lot of strong opinions being given, but aside from the "don't use it in KVM" guidance which appears to be based on GCE's engineering expertise, very little evidence that irqbalance is actually a problem.
I think it's true that in the default config, irqbalance can interfere with putting CPUs into higher C states to conserve power. However, I don't see any indication of quantitative analysis showing the impact. Recent versions of irqbalance have a '--powerthresh' argument that can be used to tell irqbalance to rebalance across fewer cores when CPU load is low, to allow some of the cores to be put into a sleep state and conserve power. My own initial testing on my desktop shows that this gets used for all of about 10 seconds at a time every few hours, before the load increases and irqbalance wakes the core back up... I would want any decision to remove irqbalance from the desktop to be based on evidence, not conjecture. At a minimum, I think what I would like to see is output from powertop showing both power consumption and CPU idle stats over a reasonable amount of time (10 minutes?), on a representative client machine, for a 2x3 matrix of configurations: - idle vs normal desktop load - irqbalance disabled vs irqbalance enabled with defaults vs irqbalance enabled with IRQBALANCE_ARGS=--powerthresh=1 System should be rebooted between each of the irqbalance configurations, as I'm not sure what does or doesn't persist in the CPU config after irqbalance exits. I am specifically not going to try to rebut the various webpages referenced here, beyond saying that there's an awful lot of these pages pointing to one other as authoritative sources on irqbalance without there actually being evidence to back them up (and a heaping spoonful of misinformation / outdated information along the way). So if we're going to make a change, there should be due diligence to demonstrate a benefit, it should not be based on Internet hype. -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to ubuntu-meta in Ubuntu. https://bugs.launchpad.net/bugs/1833322 Title: Consider removing irqbalance from default install on desktop images Status in irqbalance package in Ubuntu: New Status in ubuntu-meta package in Ubuntu: Confirmed Bug description: as per https://github.com/pop-os/default-settings/issues/60 Distribution (run cat /etc/os-release): $ cat /etc/os-release NAME="Pop!_OS" VERSION="19.04" ID=ubuntu ID_LIKE=debian PRETTY_NAME="Pop!_OS 19.04" VERSION_ID="19.04" HOME_URL="https://system76.com/pop"; SUPPORT_URL="http://support.system76.com"; BUG_REPORT_URL="https://github.com/pop-os/pop/issues"; PRIVACY_POLICY_URL="https://system76.com/privacy"; VERSION_CODENAME=disco UBUNTU_CODENAME=disco Related Application and/or Package Version (run apt policy $PACKAGE NAME): $ apt policy irqbalance irqbalance: Installed: 1.5.0-3ubuntu1 Candidate: 1.5.0-3ubuntu1 Version table: *** 1.5.0-3ubuntu1 500 500 http://us.archive.ubuntu.com/ubuntu disco/main amd64 Packages 100 /var/lib/dpkg/status $ apt rdepends irqbalance irqbalance Reverse Depends: Recommends: ubuntu-standard gce-compute-image-packages Issue/Bug Description: as per konkor/cpufreq#48 and http://konkor.github.io/cpufreq/faq/#irqbalance-detected irqbalance is technically not needed on desktop systems (supposedly it is mainly for servers), and may actually reduce performance and power savings. It appears to provide benefits only to server environments that have relatively-constant loading. If it is truly a server- oriented package, then it shouldn't be installed by default on a desktop/laptop system and shouldn't be included in desktop OS images. Steps to reproduce (if you know): This is potentially an issue with all default installs. Expected behavior: n/a Other Notes: I can safely remove it via "sudo apt purge irqbalance" without any apparent adverse side-effects. If someone is running a situation where they need it, then they always have the option of installing it from the repositories. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/irqbalance/+bug/1833322/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
