I've added the OEM Solutions Group team for awareness. I'm not sure what the final fix will be since servers' and desktops'/laptops' ideal default seem to be different, but most likely the certification tests should be adjusted if we don't end up restoring the previous behaviour of the ondemand.service unconditionally.
The latest LTS release, 20.04 is not affected so the certification test changes are probably not very urgent. -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1885730 Title: Bring back ondemand.service or switch kernel default governor for pstate - pstate now defaults to performance governor Status in linux package in Ubuntu: Confirmed Status in systemd package in Ubuntu: Invalid Status in linux source package in Focal: New Status in systemd source package in Focal: Fix Released Status in linux source package in Groovy: Confirmed Status in systemd source package in Groovy: Invalid Bug description: In a recent merge from Debian we lost ondemand.service, meaning all CPUs now run in Turbo all the time when idle, which is clearly suboptimal. The discussion in bug 1806012 seems misleading, focusing on p-state vs other drivers, when in fact, the script actually set the default governor for the pstate driver on platforms that use pstate. Everything below only looks at systems that use pstate. pstate has two governors: performance and powerstate. performance runs CPU at maximum frequency constantly, and powersave can be configured using various energy profiles energy profiles: - performance - balanced performance - balanced power - power It defaults to balanced performance, I think, but I'm not sure. Whether performance governor is faster than powersave governor is not even clear. https://www.phoronix.com/scan.php?page=article&item=linux50-pstate- cpufreq&num=5 benchmarked them, but did not benchmark the individual energy profiles. For a desktop/laptop, the expected behavior is the powersave governor with balanced_performance on AC and balanced_power on battery. I don't know about servers or VMs, but the benchmark series seems to indicate it does not really matter much performance wise. I think most other distributions configure their kernels to use the powersave governor by default, whereas we configure it to use the performance governor and then switch it later in the boot to get the maximum performance during bootup. It's not clear to me that's actually useful. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1885730/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
