Rebooting with intel_pstate=enable has fixed the issue and vastly improved the responsiveness of this laptop.
** Summary changed: - CPUs stuck at minimum frequency with ondemand cpufreq governor, even after reboot + ondemand cpufreq governor does not scale CPU freq on Sandybridge ** Description changed: I notice that turbostat shows all cpus stuck at the minimum 800MHz (see attached log) on my system, even after rebooting twice. I used "stress --cpu 8" to confirm that the frequencies remained at 800MHz even under load. It looks like the system is using the acpi-cpufreq driver with the ondemand governor (has the default been changed so it does not use intel p-state, as per https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1188647?). - The only unusual thing I had done prior to this was to boot into the - weekly build of 3.12-rc3 just prior (this kernel kept the frequencies - rather high, typically over 2GHz, ie using a lot more power than usual, - so I rebooted back into the standard kernel). + + Edit: See comment #1 below - it looks like I can manually change the cpu freq, but the governor cannot. Also, switching to use intel pstate fixes the problem. + + + The only unusual thing I had done prior to this was to boot into the weekly build of 3.12-rc3 just prior (this kernel kept the frequencies rather high, typically over 2GHz, ie using a lot more power than usual, so I rebooted back into the standard kernel). This is the contents of the files in /sys/devices/system/cpu/cpu0/cpufreq/: affected_cpus: 0 bios_limit: 2001000 cpuinfo_cur_freq: 800000 cpuinfo_max_freq: 2001000 cpuinfo_min_freq: 800000 cpuinfo_transition_latency: 10000 freqdomain_cpus: 0 1 2 3 4 5 6 7 related_cpus: 0 scaling_available_frequencies: - 2001000 2000000 1900000 1800000 1700000 1600000 1500000 1400000 1300000 1200000 1100000 1000000 900000 800000 + 2001000 2000000 1900000 1800000 1700000 1600000 1500000 1400000 1300000 1200000 1100000 1000000 900000 800000 scaling_available_governors: - conservative ondemand userspace powersave performance + conservative ondemand userspace powersave performance scaling_cur_freq: 800000 scaling_driver: acpi-cpufreq scaling_governor: ondemand scaling_max_freq: 2001000 scaling_min_freq: 800000 scaling_setspeed: <unsupported> stats: ProblemType: Bug DistroRelease: Ubuntu 13.10 Package: linux-image-3.11.0-9-generic 3.11.0-9.16 ProcVersionSignature: Ubuntu 3.11.0-9.16-generic 3.11.2 Uname: Linux 3.11.0-9-generic x86_64 ApportVersion: 2.12.5-0ubuntu1 Architecture: amd64 AudioDevicesInUse: - USER PID ACCESS COMMAND - /dev/snd/controlC0: rocko 2813 F.... pulseaudio + USER PID ACCESS COMMAND + /dev/snd/controlC0: rocko 2813 F.... pulseaudio Date: Tue Oct 1 10:13:24 2013 InstallationDate: Installed on 2012-08-25 (401 days ago) InstallationMedia: Ubuntu 12.10 "Quantal Quetzal" - Alpha amd64 (20120724.2) MachineType: Dell Inc. Dell System XPS L502X MarkForUpload: True ProcFB: 0 inteldrmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.11.0-9-generic root=UUID=67083065-b92e-4596-a218-817c1dfc8ae7 ro crashkernel=384M-2G:64M,2G-:128M quiet splash vt.handoff=7 RelatedPackageVersions: - linux-restricted-modules-3.11.0-9-generic N/A - linux-backports-modules-3.11.0-9-generic N/A - linux-firmware 1.115 + linux-restricted-modules-3.11.0-9-generic N/A + linux-backports-modules-3.11.0-9-generic N/A + linux-firmware 1.115 SourcePackage: linux UpgradeStatus: Upgraded to saucy on 2013-09-01 (30 days ago) dmi.bios.date: 05/29/2012 dmi.bios.vendor: Dell Inc. dmi.bios.version: A11 dmi.board.name: 0NJT03 dmi.board.vendor: Dell Inc. dmi.board.version: A00 dmi.chassis.type: 8 dmi.chassis.vendor: Dell Inc. dmi.chassis.version: 0.1 dmi.modalias: dmi:bvnDellInc.:bvrA11:bd05/29/2012:svnDellInc.:pnDellSystemXPSL502X:pvr:rvnDellInc.:rn0NJT03:rvrA00:cvnDellInc.:ct8:cvr0.1: dmi.product.name: Dell System XPS L502X dmi.sys.vendor: Dell Inc. -- 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/1233479 Title: ondemand cpufreq governor does not scale CPU freq on Sandybridge Status in “linux” package in Ubuntu: Confirmed Bug description: I notice that turbostat shows all cpus stuck at the minimum 800MHz (see attached log) on my system, even after rebooting twice. I used "stress --cpu 8" to confirm that the frequencies remained at 800MHz even under load. It looks like the system is using the acpi-cpufreq driver with the ondemand governor (has the default been changed so it does not use intel p-state, as per https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1188647?). Edit: See comment #1 below - it looks like I can manually change the cpu freq, but the governor cannot. Also, switching to use intel pstate fixes the problem. The only unusual thing I had done prior to this was to boot into the weekly build of 3.12-rc3 just prior (this kernel kept the frequencies rather high, typically over 2GHz, ie using a lot more power than usual, so I rebooted back into the standard kernel). This is the contents of the files in /sys/devices/system/cpu/cpu0/cpufreq/: affected_cpus: 0 bios_limit: 2001000 cpuinfo_cur_freq: 800000 cpuinfo_max_freq: 2001000 cpuinfo_min_freq: 800000 cpuinfo_transition_latency: 10000 freqdomain_cpus: 0 1 2 3 4 5 6 7 related_cpus: 0 scaling_available_frequencies: 2001000 2000000 1900000 1800000 1700000 1600000 1500000 1400000 1300000 1200000 1100000 1000000 900000 800000 scaling_available_governors: conservative ondemand userspace powersave performance scaling_cur_freq: 800000 scaling_driver: acpi-cpufreq scaling_governor: ondemand scaling_max_freq: 2001000 scaling_min_freq: 800000 scaling_setspeed: <unsupported> stats: ProblemType: Bug DistroRelease: Ubuntu 13.10 Package: linux-image-3.11.0-9-generic 3.11.0-9.16 ProcVersionSignature: Ubuntu 3.11.0-9.16-generic 3.11.2 Uname: Linux 3.11.0-9-generic x86_64 ApportVersion: 2.12.5-0ubuntu1 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: rocko 2813 F.... pulseaudio Date: Tue Oct 1 10:13:24 2013 InstallationDate: Installed on 2012-08-25 (401 days ago) InstallationMedia: Ubuntu 12.10 "Quantal Quetzal" - Alpha amd64 (20120724.2) MachineType: Dell Inc. Dell System XPS L502X MarkForUpload: True ProcFB: 0 inteldrmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.11.0-9-generic root=UUID=67083065-b92e-4596-a218-817c1dfc8ae7 ro crashkernel=384M-2G:64M,2G-:128M quiet splash vt.handoff=7 RelatedPackageVersions: linux-restricted-modules-3.11.0-9-generic N/A linux-backports-modules-3.11.0-9-generic N/A linux-firmware 1.115 SourcePackage: linux UpgradeStatus: Upgraded to saucy on 2013-09-01 (30 days ago) dmi.bios.date: 05/29/2012 dmi.bios.vendor: Dell Inc. dmi.bios.version: A11 dmi.board.name: 0NJT03 dmi.board.vendor: Dell Inc. dmi.board.version: A00 dmi.chassis.type: 8 dmi.chassis.vendor: Dell Inc. dmi.chassis.version: 0.1 dmi.modalias: dmi:bvnDellInc.:bvrA11:bd05/29/2012:svnDellInc.:pnDellSystemXPSL502X:pvr:rvnDellInc.:rn0NJT03:rvrA00:cvnDellInc.:ct8:cvr0.1: dmi.product.name: Dell System XPS L502X dmi.sys.vendor: Dell Inc. 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