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** 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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