** Tags added: kernel-unable-to-test-upstream -- 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/1386473
Title: Not using all cores after upgrade to 14.10 Status in “linux” package in Ubuntu: Incomplete Bug description: I have a computer with two cpus with 4 cores each (physical) but htop is only showing activity on two of these 8 cores (number 1 and 3). Also, if I run "stress -c 8" top shows only 25% cpu usage. I've rebooted the machine and the problem persists. I also took a look at the BIOS settings and found nothing there that looked suspicious. If I run 'stress -c 8' only two cores go to 100% in htop as stated above (cores 1 and 3). If I run 'stress -c 1', one core goes to 100% (either core 1 or 3). If I run taskset -cp <coreid> <pid> I can control which core the process is run on. I can actually move it to any core that I want (1, 3 or any other one)! So the cores are there... the kernel just doesn't seem to use it unless I explicitly tell it to with taskset. I've verified that this is a regression when moving from [lxk]ubuntu 14.04 to 14.10. I used pristine lubuntu 14.10 and 14.04 usb sticks to test this out and verified that a cpu sysbench test using 8 threads took ~15 sec on 14.04 but ~55 sec on 14.10. The computer this is happening on is a Dell Precision T5400 tower workstation. ProblemType: Bug DistroRelease: Ubuntu 14.10 Package: linux-image-3.16.0-23-generic 3.16.0-23.31 ProcVersionSignature: Ubuntu 3.16.0-23.31-generic 3.16.4 Uname: Linux 3.16.0-23-generic x86_64 NonfreeKernelModules: nvidia ApportVersion: 2.14.7-0ubuntu8 Architecture: amd64 CRDA: Error: [Errno 2] No such file or directory: 'iw' CurrentDesktop: KDE Date: Tue Oct 28 00:46:25 2014 HibernationDevice: RESUME=UUID=20536d9f-ef05-46dd-a104-47367e464fcd InstallationDate: Installed on 2014-02-05 (264 days ago) InstallationMedia: Ubuntu-Server 13.10 "Saucy Salamander" - Release amd64 (20131016) IwConfig: eth0 no wireless extensions. lo no wireless extensions. MachineType: Dell Inc. Precision WorkStation T5400 ProcFB: ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.16.0-23-generic root=UUID=28fc4c4c-cecd-4abe-a788-28f69e745845 ro splash quiet RelatedPackageVersions: linux-restricted-modules-3.16.0-23-generic N/A linux-backports-modules-3.16.0-23-generic N/A linux-firmware 1.138 RfKill: SourcePackage: linux UpgradeStatus: Upgraded to utopic on 2014-10-24 (3 days ago) dmi.bios.date: 02/01/2008 dmi.bios.vendor: Dell Inc. dmi.bios.version: A01 dmi.board.name: 0RW203 dmi.board.vendor: Dell Inc. dmi.board.version: A00 dmi.chassis.type: 7 dmi.chassis.vendor: Dell Inc. dmi.modalias: dmi:bvnDellInc.:bvrA01:bd02/01/2008:svnDellInc.:pnPrecisionWorkStationT5400:pvr:rvnDellInc.:rn0RW203:rvrA00:cvnDellInc.:ct7:cvr: dmi.product.name: Precision WorkStation T5400 dmi.sys.vendor: Dell Inc. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1386473/+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
