I got tired of this buggy laptop so I gave it away and bought a new Dell XPS 13 with preinstalled Ubuntu. It sometimes also freezes, but I don't have time to debug everything. I really hope that in the future all pre- installed Ubuntu machines I buy would work perfectly. Thanks for your efforts towards that!
-- 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/998204 Title: Intel chipset driver bug on Ubuntu certified Dell Latitude E5420: connecting power cord makes kworker run amok Status in “linux” package in Ubuntu: Incomplete Bug description: I've noticed that sometimes when I'm running on battery and then insert the power cord, the system slows down significantly. When I remove the power cord, it runs fine again, and when I reattach the power cord the system slows down again. I'm running the latest Ubuntu 12.04 with all updates on a pre- installed Dell Latitude E5420 that is supposed to work perfectly with Ubuntu, since it is officially certified. While the sluggishness happens, running 'top' shows several kworker processes: top - 21:29:24 up 14:01, 4 users, load average: 1.91, 2.16, 2.06 Tasks: 208 total, 3 running, 202 sleeping, 0 stopped, 3 zombie Cpu(s): 5.6%us, 2.2%sy, 0.0%ni, 91.7%id, 0.5%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 1891244k total, 1782568k used, 108676k free, 22512k buffers Swap: 2004988k total, 812400k used, 1192588k free, 550600k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 16561 otto 20 0 526m 15m 7796 S 14 0.9 1:10.79 gnome-system-mo 16534 root 20 0 0 0 0 R 7 0.0 0:16.66 kworker/1:2 1215 root 20 0 275m 25m 4472 S 6 1.4 11:31.39 Xorg 16362 root 20 0 0 0 0 S 3 0.0 0:10.00 kworker/0:1 1889 otto 20 0 1470m 64m 12m S 3 3.5 10:07.92 compiz 16287 root 20 0 0 0 0 S 3 0.0 0:13.85 kworker/3:2 2306 otto 20 0 652m 14m 5056 S 2 0.8 0:31.76 gnome-terminal 17304 otto 20 0 17480 1384 964 R 1 0.1 0:00.03 top Using commands sudo perf record -ag sleep 30 sudo perf report I was able to find out that the kworker threads running amok are due to the Intel I2C driver: ... 2.91% kworker/1:2 [kernel.kallsyms] [k] na | --- native_read_tsc | |--62.97%-- delay_tsc | | | |--53.92%-- __udelay | | | | | |--50.48%-- sclhi | | | | | | | |--94.88%-- i2c_outb ... 2.76% kworker/1:0 [kernel.kallsyms] [k] na | --- native_read_tsc | |--69.42%-- delay_tsc | | | |--58.89%-- __udelay | | | | | |--47.38%-- sclhi | | | | | | | |--88.80%-- i2c_outb ... 2.20% kworker/0:0 [kernel.kallsyms] [k] na | --- native_read_tsc | |--64.58%-- delay_tsc | | | |--63.38%-- __udelay | | | | | |--47.18%-- i2c_outb.isra.4 | | | try_address | | | bit_doAddress.isra.7 | | | bit_xfer | | | intel_i2c_quirk_xfer ... I've attached the entire perf report output for your analysis. To view the stack of the process I ran cat /proc/16287/stack > pid-16287-stack.txt, which is also attached. Please fix the Intel driver so that it does not spawn any wild kworker processes and publish the fix in the 12.04 mainline kernel. I've noticed that others have this sympoms too, but I guess few are knowledgeable enough to file a proper bug report, so I decided to do one. For example, see comment #27 at https://bugs.launchpad.net/ubuntu/+source/linux/+bug/887793/comments/27 or http://askubuntu.com/questions/106187/lenovo-thinkpad-l520-slows-down-when-ac-power-adapter-is-plugged-in ProblemType: Bug DistroRelease: Ubuntu 12.04 Package: linux-image-3.2.0-24-generic 3.2.0-24.37 ProcVersionSignature: Ubuntu 3.2.0-24.37-generic 3.2.14 Uname: Linux 3.2.0-24-generic x86_64 AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.24. ApportVersion: 2.0.1-0ubuntu7 Architecture: amd64 ArecordDevices: **** List of CAPTURE Hardware Devices **** card 0: PCH [HDA Intel PCH], device 0: STAC92xx Analog [STAC92xx Analog] Subdevices: 1/1 Subdevice #0: subdevice #0 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: otto 1897 F.... pulseaudio Card0.Amixer.info: Card hw:0 'PCH'/'HDA Intel PCH at 0x93d40000 irq 44' Mixer name : 'Intel CougarPoint HDMI' Components : 'HDA:111d76e7,1028049b,00100102 HDA:80862805,80860101,00100000' Controls : 37 Simple ctrls : 13 CheckboxSubmission: d8cea1222d756fdd8d727e88eb0e4a11 CheckboxSystem: d00f84de8a555815fa1c4660280da308 Date: Fri May 11 22:05:56 2012 EcryptfsInUse: Yes HibernationDevice: RESUME=UUID=affcc5fa-3b4d-40de-aec2-259585dbd9e3 InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Beta amd64 (20110413) MachineType: Dell Inc. Latitude E5420 ProcFB: 0 inteldrmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.2.0-24-generic root=UUID=0fc070a9-5f2c-41fc-b8f0-6e0a91fa1426 ro quiet i915.semaphores=1 pcie_aspm=force PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: Home directory /home/otto not ours. No PulseAudio daemon running, or not running as session daemon. RelatedPackageVersions: linux-restricted-modules-3.2.0-24-generic N/A linux-backports-modules-3.2.0-24-generic N/A linux-firmware 1.79 SourcePackage: linux StagingDrivers: mei UpgradeStatus: Upgraded to precise on 2012-04-09 (31 days ago) dmi.bios.date: 02/22/2011 dmi.bios.vendor: Dell Inc. dmi.bios.version: A00 dmi.board.name: 08N8FC dmi.board.vendor: Dell Inc. dmi.board.version: A01 dmi.chassis.type: 9 dmi.chassis.vendor: Dell Inc. dmi.modalias: dmi:bvnDellInc.:bvrA00:bd02/22/2011:svnDellInc.:pnLatitudeE5420:pvr01:rvnDellInc.:rn08N8FC:rvrA01:cvnDellInc.:ct9:cvr: dmi.product.name: Latitude E5420 dmi.product.version: 01 dmi.sys.vendor: Dell Inc. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/998204/+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
