For the decision to re-enable the intel pstate driver by default or not, the suggestion is to be cautious. The driver keeps changing in rather fundamental ways, such that one can never be sure how it is going to perform. I will attach two graphs to (hopefully) help make my point.
The first graph demonstrates a dramatic difference in CPU frequency scaling response as a function of load between kernel 3.12 and 3.15RC2 at a fixed idle (sleep) / work frequency. The second graph (to be posted in a moment) demonstrates a dramatic difference in CPU scaling frequency as a function of idle (sleep) /work frequency at a fixed load. Don't get me wrong here, as I am a proponent of the intel_pstate driver, but I am concerned about how its response to stimulus keeps changing. ** Attachment added: "CPU 7 frequency vs load. Turbo on. Kernels 3.15RC2 and 3.12" https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1188647/+attachment/4097698/+files/k315rc2_k312_load_sweep_200.png -- 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/1188647 Title: Please change intel_pstate default to disable Status in “linux” package in Ubuntu: Fix Released Bug description: 3.9 introduced a new default governor on SandyBridge CPUs called INTEL_PSTATE which, when built in and enabled (the default), removes all other governors (like our usual default, ondemand). 3.10 extended this to Ivybridge generation CPUs. In theory, this isn't an awful thing, as the new Intel pstate governor should be higher performance and give better power savings. In theory. In practice, it drives my CPUs to max frequency nearly constantly, spins my fans like mad and, somehow, does all of this while also eating enough CPU time in kernel threads to make my machine choppy, unresponsive, and unable to do simple things like play videos when I get off work. Therefore, I propose that we, for now, toggle intel_pstate to disable by default (I am using intel_pstate=disable on my command line right now, with great success), so it's still built in, and people can play with it, but it's off by default. ProblemType: Bug DistroRelease: Ubuntu 13.10 Package: linux-image-3.9.0-4-generic 3.9.0-4.9 ProcVersionSignature: Ubuntu 3.9.0-4.9-generic 3.9.4 Uname: Linux 3.9.0-4-generic x86_64 ApportVersion: 2.10.2-0ubuntu1 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: adconrad 2574 F.... pulseaudio CurrentDmesg: [ 30.633035] init: plymouth-stop pre-start process (2079) terminated with status 1 [ 36.086916] br0: port 1(eth0) entered forwarding state Date: Fri Jun 7 08:48:56 2013 HibernationDevice: RESUME=UUID=73040efa-baec-458a-8307-3bca07b26c3c InstallationDate: Installed on 2012-12-09 (179 days ago) InstallationMedia: Ubuntu 13.04 "Raring Ringtail" - Alpha amd64 (20121209) MachineType: LENOVO 4173LPB MarkForUpload: True ProcFB: 0 inteldrmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.9.0-4-generic root=UUID=2222aad5-ef31-4428-973f-71740fc7cb6a ro intel_pstate=disable quiet splash vt.handoff=7 RelatedPackageVersions: linux-restricted-modules-3.9.0-4-generic N/A linux-backports-modules-3.9.0-4-generic N/A linux-firmware 1.109 SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 09/13/2012 dmi.bios.vendor: LENOVO dmi.bios.version: 8CET55WW (1.35 ) dmi.board.asset.tag: Not Available dmi.board.name: 4173LPB dmi.board.vendor: LENOVO dmi.board.version: Not Available dmi.chassis.asset.tag: No Asset Information dmi.chassis.type: 10 dmi.chassis.vendor: LENOVO dmi.chassis.version: Not Available dmi.modalias: dmi:bvnLENOVO:bvr8CET55WW(1.35):bd09/13/2012:svnLENOVO:pn4173LPB:pvrThinkPadT420s:rvnLENOVO:rn4173LPB:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable: dmi.product.name: 4173LPB dmi.product.version: ThinkPad T420s dmi.sys.vendor: LENOVO To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1188647/+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
