** Changed in: linux (Ubuntu)
Importance: Medium => Low
** Changed in: linux (Ubuntu)
Status: Incomplete => Confirmed
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https://bugs.launchpad.net/bugs/1058864
Title:
Poor mutex and semaphore performance
Status in “linux” package in Ubuntu:
Confirmed
Bug description:
I noticed the results of this blog post:
http://mr-edd.co.uk/blog/sad_state_of_osx_pthread_mutex_t
and I was curious if the same sort of issue existed with the linux kernel and
if it would shed any light on Bug #1058854
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1058854
The results don't appear to be as bad as those seen on Mac OS X, but they
definitely are a lot poorer than I expected/hoped they would be. The code that
builds on Linux is now available on that blog port and I created a git repo
with the history here:
https://github.com/daveisfera/test_mutex
Here are the results from running it on the the same HP Pavilion dm4 that as
the results from Bug #1058854:
mutex
1 thread real 0m 0.514s user 0m 0.512s sys 0m 0.000s
2 threads real 0m 4.382s user 0m 5.176s sys 0m 3.544s
4 threads real 0m 9.953s user 0m 9.709s sys 0m22.417s
8 threads real 0m20.984s user 0m14.973s sys 1m 8.256s
16 threads real 0m38.725s user 0m28.426s sys 2m 5.484s
benaphore
1 thread real 0m 0.324s user 0m 0.312s sys 0m 0.008s
2 threads real 0m 6.372s user 0m 6.380s sys 0m 5.572s
4 threads real 0m17.820s user 0m12.273s sys 0m42.495s
8 threads real 0m40.266s user 0m25.626s sys 2m14.400s
16 threads real 1m40.090s user 0m52.939s sys 5m45.802s
mutex2
1 thread real 0m 0.325s user 0m 0.320s sys 0m 0.004s
2 threads real 0m 0.730s user 0m 0.816s sys 0m 0.384s
4 threads real 0m 2.328s user 0m 3.388s sys 0m 5.704s
8 threads real 0m 4.096s user 0m 5.328s sys 0m10.705s
16 threads real 0m 7.584s user 0m 9.609s sys 0m20.401s
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AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.24.
ApportVersion: 2.0.1-0ubuntu13
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: dlj 1876 F.... pulseaudio
Card0.Amixer.info:
Card hw:0 'PCH'/'HDA Intel PCH at 0xc0800000 irq 50'
Mixer name : 'Intel CougarPoint HDMI'
Components : 'HDA:111d76e0,103c1793,00100102
HDA:80862805,103c1793,00100000'
Controls : 22
Simple ctrls : 10
DistroRelease: Ubuntu 12.04
InstallationMedia: Ubuntu 12.04.1 LTS "Precise Pangolin" - Release amd64
(20120823.1)
MachineType: Hewlett-Packard HP Pavilion dm4 Notebook PC
Package: linux (not installed)
ProcEnviron:
TERM=xterm
PATH=(custom, no user)
LANG=en_US.UTF-8
SHELL=/bin/bash
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.2.0-31-generic
root=UUID=162256F02256D479 loop=/hostname/disks/root.disk ro quiet splash
vt.handoff=7
ProcVersionSignature: Ubuntu 3.2.0-31.50-generic 3.2.28
RelatedPackageVersions:
linux-restricted-modules-3.2.0-31-generic N/A
linux-backports-modules-3.2.0-31-generic N/A
linux-firmware 1.79.1
StagingDrivers: rts_pstor mei
Tags: precise running-unity staging
Uname: Linux 3.2.0-31-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo
dmi.bios.date: 01/17/2012
dmi.bios.vendor: Hewlett-Packard
dmi.bios.version: F.08
dmi.board.asset.tag: Base Board Asset Tag
dmi.board.name: 1793
dmi.board.vendor: Hewlett-Packard
dmi.board.version: 41.1C
dmi.chassis.asset.tag: Chassis Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: Hewlett-Packard
dmi.chassis.version: Chassis Version
dmi.modalias:
dmi:bvnHewlett-Packard:bvrF.08:bd01/17/2012:svnHewlett-Packard:pnHPPaviliondm4NotebookPC:pvr068E100002204710000622100:rvnHewlett-Packard:rn1793:rvr41.1C:cvnHewlett-Packard:ct10:cvrChassisVersion:
dmi.product.name: HP Pavilion dm4 Notebook PC
dmi.product.version: 068E100002204710000622100
dmi.sys.vendor: Hewlett-Packard
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