Public bug reported:
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.
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug utopic
--
You received this bug notification because you are a member of Ubuntu
Bugs, which is subscribed to Ubuntu.
https://bugs.launchpad.net/bugs/1386473
Title:
Not using all cores after upgrade to 14.10
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1386473/+subscriptions
--
ubuntu-bugs mailing list
ubuntu-bugs@lists.ubuntu.com
https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
