Something I was not previously aware of that informs this a bit more, is that in some BIOS modes (apparently HP uses this extensively, unsure about Dell and others) you get a "Collaborative Power Control" mode, which sets the scaling_driver to pcc-cpufreq (as opposed to cpufreq) and is some weird hybrid of OS+BIOS defined behavior.
In the case of these collaborative modes, the exact behavior is probably wildly different based on what the BIOS is doing and likely would explain why we get weird and inconsistent performance behavior. Unclear to me if such BIOS modes will still use intel_pstate or not.. something I'd have to look into. Or whether it's specific to pre-pstate. Some more information about collaborative mode in this bug: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1447763 -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to systemd in Ubuntu. https://bugs.launchpad.net/bugs/1806012 Title: set-cpufreq: 'powersave' governor configuration sanity on ubuntu server Status in systemd package in Ubuntu: In Progress Status in systemd source package in Xenial: In Progress Status in systemd source package in Bionic: In Progress Status in systemd source package in Cosmic: In Progress Status in systemd source package in Disco: In Progress Bug description: Whilst debugging 'slow instance performance' on a Ubuntu Bionic based cloud, I observed that the default cpu governor configuration was set to 'powersave'; toggling this to 'performance' (while in not anyway a particularly green thing todo) resulted in the instance slowness disappearing and the cloud performance being as expected (based on a prior version of the deploy on Ubuntu Xenial). AFAICT Xenial does the same thing albeit in a slight different way, but we definitely did not see the same performance laggy-ness under a Xenial based cloud. Raising against systemd (as this package sets the governor to 'powersave') - I feel that the switch to 'performance' although appropriate then obscures what might be a performance/behavioural difference in the underlying kernel when a machine is under load. ProblemType: Bug DistroRelease: Ubuntu 18.04 Package: systemd 237-3ubuntu10.9 ProcVersionSignature: Ubuntu 4.15.0-39.42-generic 4.15.18 Uname: Linux 4.15.0-39-generic x86_64 ApportVersion: 2.20.9-0ubuntu7.5 Architecture: amd64 Date: Fri Nov 30 10:05:46 2018 Lsusb: Bus 002 Device 002: ID 8087:8002 Intel Corp. Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 001 Device 003: ID 413c:a001 Dell Computer Corp. Hub Bus 001 Device 002: ID 8087:800a Intel Corp. Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub MachineType: Dell Inc. PowerEdge R630 ProcEnviron: TERM=xterm-256color PATH=(custom, no user) XDG_RUNTIME_DIR=<set> LANG=C.UTF-8 SHELL=/bin/bash ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-4.15.0-39-generic root=UUID=a361a524-47eb-46c3-8a04-e5eaa65188c9 ro hugepages=103117 iommu=pt intel_iommu=on SourcePackage: systemd UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 11/08/2016 dmi.bios.vendor: Dell Inc. dmi.bios.version: 2.3.4 dmi.board.name: 02C2CP dmi.board.vendor: Dell Inc. dmi.board.version: A03 dmi.chassis.type: 23 dmi.chassis.vendor: Dell Inc. dmi.modalias: dmi:bvnDellInc.:bvr2.3.4:bd11/08/2016:svnDellInc.:pnPowerEdgeR630:pvr:rvnDellInc.:rn02C2CP:rvrA03:cvnDellInc.:ct23:cvr: dmi.product.name: PowerEdge R630 dmi.sys.vendor: Dell Inc. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1806012/+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
