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[Brad Figg <brad.figg@xxxxxxxxxxxxx>]

This bug is missing log files that will aid in diagnosing the problem.
>From a terminal window please run:

apport-collect 1073148

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable
to run this command, please add a comment stating that fact and change
the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the
Ubuntu Kernel Team.

** Changed in: linux (Ubuntu)
       Status: New => Incomplete

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https://bugs.launchpad.net/bugs/1073148

Title:
  [960GM/U3S3 FX] Higher than expected cpu overhead on using multiple
  cores

Status in The Linux Kernel:
  Unknown
Status in “linux” package in Ubuntu:
  Incomplete

Bug description:
  I'm using Ubuntu 13.04 dev and have noticed a high cpu overhead if a
  process is using multiple threads and computing them on different
  cores. To measure this I have written a little script in Python which
  I will attach.

  The script will create 2 threads which are using only a little time of
  a cpu core. On my AMD Phenom II X6 1045T the Linux kernel will assign
  the 2 threads on 2 cores which will use a total cpu time of 40% from a
  maximum of 600%. But if I'm using "taskset -ap 0x00000001
  pid_of_script" the 2 threads will be assigned to 1 core and the total
  cpu usage will be only 25% from 600%.

  I'm wondering why there is a cpu overhead of 60% if the Linux kernel is using 2 cores instead of 1 core.
  ---
  AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.25.
  AplayDevices:
   **** List of PLAYBACK Hardware Devices ****
   card 0: SB [HDA ATI SB], device 0: ALC662 rev1 Analog [ALC662 rev1 Analog]
     Subdevices: 0/1
     Subdevice #0: subdevice #0
  ApportVersion: 2.6.1-0ubuntu6
  Architecture: amd64
  AudioDevicesInUse:
   USER        PID ACCESS COMMAND
   /dev/snd/controlC0:  sworddragon   2374 F.... plugin-containe
   /dev/snd/pcmC0D0p:   sworddragon   2374 F...m plugin-containe
   /dev/snd/timer:      sworddragon   2374 f.... plugin-containe
  CRDA: Error: [Errno 2] No such file or directory
  Card0.Amixer.info:
   Card hw:0 'SB'/'HDA ATI SB at 0xf9ff4000 irq 16'
     Mixer name	: 'Realtek ALC662 rev1'
     Components	: 'HDA:10ec0662,18497662,00100101'
     Controls      : 33
     Simple ctrls  : 18
  CurrentDmesg:
   Error: command ['sh', '-c', 'dmesg | comm -13 --nocheck-order /var/log/dmesg -'] failed with exit code 1: comm: /var/log/dmesg: No such file or directory
   dmesg: write failed: Broken pipe
  DistroRelease: Ubuntu 13.04
  EcryptfsInUse: Yes
  IwConfig: Error: [Errno 2] No such file or directory
  Lsusb: Error: [Errno 2] No such file or directory
  MachineType: To Be Filled By O.E.M. To Be Filled By O.E.M.
  MarkForUpload: True
  NonfreeKernelModules: nvidia
  Package: linux (not installed)
  ProcEnviron:
   TERM=xterm
   PATH=(custom, no user)
   LANG=de_DE.UTF-8
   SHELL=/bin/bash
  ProcFB: 0 VESA VGA
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.5.0-17-generic root=UUID=f1ce7323-74dc-46f7-95f7-887cc54403e7 ro
  ProcVersionSignature: Ubuntu 3.5.0-17.28-generic 3.5.5
  RfKill: Error: [Errno 2] No such file or directory
  Tags:  raring
  Uname: Linux 3.5.0-17-generic x86_64
  UpgradeStatus: No upgrade log present (probably fresh install)
  UserGroups: adm cdrom dialout lpadmin plugdev sambashare sudo
  dmi.bios.date: 05/21/2012
  dmi.bios.vendor: American Megatrends Inc.
  dmi.bios.version: P1.20
  dmi.board.asset.tag: BC5FF4739C55
  dmi.board.name: 960GM/U3S3 FX
  dmi.board.vendor: ASRock
  dmi.chassis.asset.tag: To Be Filled By O.E.M.
  dmi.chassis.type: 3
  dmi.chassis.vendor: To Be Filled By O.E.M.
  dmi.chassis.version: To Be Filled By O.E.M.
  dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrP1.20:bd05/21/2012:svnToBeFilledByO.E.M.:pnToBeFilledByO.E.M.:pvrToBeFilledByO.E.M.:rvnASRock:rn960GM/U3S3FX:rvr:cvnToBeFilledByO.E.M.:ct3:cvrToBeFilledByO.E.M.:
  dmi.product.name: To Be Filled By O.E.M.
  dmi.product.version: To Be Filled By O.E.M.
  dmi.sys.vendor: To Be Filled By O.E.M.

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